Optical waveguide element and method for manufacturing optical waveguide element

Abstract

To relax positional accuracy when a compound semiconductor waveguide including a light source or the like is stuck to an Si optical waveguide.SOLUTION: The semiconductor optical device includes a clad, a silicon waveguide core embedded in the clad and extending in parallel with the upper surface of the clad, and a compound semiconductor thin film waveguide extending in parallel with the upper surface of the clad on the upper surface of the clad on the upper side of the silicon waveguide core. In a region where the silicon waveguide core and the compound semiconductor thin film waveguide overlap each other, one or both of the silicon waveguide core and the compound semiconductor thin film waveguide are provided with a width tapered structure in which a width, which is a length in a width direction orthogonal to both of a direction in which the silicon waveguide core extends, changes along a propagation direction of light. A maximum width of one or both of the silicon waveguide core and the compound semiconductor thin film waveguide is 7 μm or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical waveguide element that combines a silicon optical waveguide with a compound semiconductor, and a manufacturing method thereof, and more particularly to an optical waveguide element suitable for use in many fields, such as optical biosensors and optical communications, and a manufacturing method thereof. [Background technology]

[0002] In recent years, Si optical waveguide technology, which uses silicon (Si) as a waveguide material with the aim of miniaturization and mass production, has begun to attract attention. However, it is difficult to realize a light source using Si. For this reason, compound semiconductor light sources using III-V group compound semiconductors are sometimes used as light sources.

[0003] Many methods have been proposed for combining compound semiconductor light sources with Si optical waveguides.

[0004] One is to use a completely external light source, in which light is input to the Si optical waveguide via a grating coupler.

[0005] Another method is to integrate a light source on the same chip as the Si optical waveguide by directly growing compound semiconductors, but it is difficult to achieve a high-performance light source using this method.

[0006] Another method is to connect the light source to the end of the optical waveguide via a spot size converter, but this requires alignment work to align the optical axis, which makes it unsuitable for mass production.

[0007] In contrast to this method, a method has been proposed in which a light source is attached to a Si optical waveguide from above in order to enable mass production (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent Publication 2021-093627 Summary of the Invention [Problem to be solved by the invention]

[0009] However, the above-mentioned conventional method requires strict positional accuracy and is therefore not a very practical method.

[0010] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical waveguide element in which the positional accuracy requirement is relaxed when a compound semiconductor waveguide including a light source and the like is attached to a Si optical waveguide, and a method for manufacturing the same. [Means for solving the problem]

[0011] To achieve the above-mentioned object, the optical waveguide element of the present invention comprises a cladding, a silicon waveguide core embedded in the cladding and extending parallel to the upper surface of the cladding, and a compound semiconductor thin film waveguide extending parallel to the upper surface of the cladding on the upper surface of the cladding above the silicon waveguide core. In the region where the silicon waveguide core and the compound semiconductor thin film waveguide overlap, one or both of the silicon waveguide core and the compound semiconductor thin film waveguide have a width tapered structure in which the width, which is the length in a width direction perpendicular to both the direction in which the silicon waveguide core extends, changes along the direction of light propagation. The maximum width of one or both of the silicon waveguide core and the compound semiconductor thin film waveguide is 7 μm or more.

[0012] According to a preferred embodiment of the optical waveguide element of the present invention, the distance between the silicon waveguide core and the compound semiconductor thin film waveguide in a direction perpendicular to the upper surface of the cladding is 200 nm or more.

[0013] According to another preferred embodiment of the optical waveguide element of the present invention, the silicon waveguide core comprises a first tapered silicon waveguide core and a second tapered silicon waveguide core arranged in series from one end face side of the cladding in the extension direction. The first tapered silicon waveguide core gradually increases in width from one end face of the cladding toward the second tapered silicon waveguide core, the second tapered silicon waveguide core gradually decreases in width from the first tapered silicon waveguide core toward the other end face of the cladding, and the compound semiconductor thin film waveguide gradually increases in width from one end face of the cladding toward the other end face, and in a region where the second tapered silicon waveguide core and the compound semiconductor thin film waveguide overlap, there is a location where the width of the second tapered silicon waveguide core and the width of the compound semiconductor thin film waveguide are equal, and the maximum width of the second tapered silicon waveguide core and the compound semiconductor thin film waveguide is 7 μm or more and 14 μm or less.

[0014] According to another preferred embodiment of the optical waveguide element of the present invention, the optical waveguide element further comprises a rib waveguide, a tapered waveguide, and a connecting waveguide, each of which has a ridge portion and a terrace portion, wherein the rib waveguide, the tapered waveguide, the connecting waveguide, and the compound semiconductor thin film waveguide are connected in this order, the thicknesses of the ridge portions of the rib waveguide, the tapered waveguide, and the connecting waveguide are equal to each other, and the thicknesses of the terrace portions of the rib waveguide, the tapered waveguide, and the connecting waveguide are equal to the thickness of the compound semiconductor thin film waveguide.

[0015] The width of the rib waveguide is constant along the propagation direction, the width of the ridge portion of the rib waveguide is constant along the propagation direction, the width of the tapered waveguide is constant along the propagation direction and is equal to the width of the rib waveguide, the width of the ridge portion of the tapered waveguide gradually narrows toward the connecting waveguide, and at the connecting end faces of the rib waveguide and the tapered waveguide, the widths of the ridge portions of the rib waveguide and the tapered waveguide are equal to each other.

[0016] The width of the connecting waveguide gradually increases toward the compound semiconductor waveguide, and the ridge portion of the connecting waveguide has a constant width along the propagation direction and is provided with a length from the end of the connecting waveguide on the tapered waveguide side that is shorter than the length of the connecting waveguide along the propagation direction. At the connecting end faces of the tapered waveguide and the connecting waveguide, the widths of the tapered waveguide and the connecting waveguide are equal to each other, and the widths of the ridge portions of the tapered waveguide and the connecting waveguide are equal to each other, and at the connecting end faces of the connecting waveguide and the compound semiconductor thin film waveguide, the widths of the connecting waveguide and the compound semiconductor thin film waveguide are equal to each other.

[0017] According to another preferred embodiment of the optical waveguide element of the present invention, the optical waveguide element further comprises a rib waveguide and a tapered waveguide, each of which has a ridge portion and a terrace portion, and the rib waveguide, the tapered waveguide, and the compound semiconductor thin film waveguide are connected in series in this order.

[0018] The thicknesses of the rib waveguide and the ridge portions of the tapered waveguide are equal to each other, the thicknesses of the terrace portions of the rib waveguide and the tapered waveguide are equal to the thickness of the compound semiconductor thin film waveguide, the width of the rib waveguide is constant along the propagation direction, the width of the ridge portions of the rib waveguide is constant along the propagation direction, and at the connection end faces of the rib waveguide and the tapered waveguide, the widths of the rib waveguide and the tapered waveguide are equal to each other, and the widths of the ridge portions of the rib waveguide and the tapered waveguide are equal to each other. The width of the tapered waveguide and the width of the ridge portion of the tapered waveguide gradually narrow toward the compound semiconductor thin film waveguide, and at the connection end face of the tapered waveguide and the compound semiconductor thin film waveguide, the widths of the tapered waveguide and the compound semiconductor thin film waveguide are equal to each other, and the width of the compound semiconductor thin film waveguide gradually narrows as it moves away from the tapered waveguide along the propagation direction. The width of the silicon waveguide core is constant along the propagation direction, and the width of the silicon waveguide core is 9 μm or more and 20 μm or less.

[0019] According to another preferred embodiment of the optical waveguide element of the present invention, a grating is formed in the silicon waveguide core, the equivalent refractive index of which changes periodically along the propagation direction. According to a further preferred embodiment of the optical waveguide element of the present invention, the phase or period of the grating varies depending on the position in the width direction of the silicon waveguide core.

[0020] According to another preferred embodiment of the optical waveguide element of the present invention, the silicon waveguide core comprises a constant-width silicon waveguide core and a tapered silicon waveguide core, which are arranged in series in this order in the extending direction.

[0021] the width of the constant-width silicon waveguide core is constant along the propagation direction, the width of the tapered silicon waveguide core gradually narrows from the constant-width silicon waveguide core toward the other end face of the cladding, the widths of the constant-width silicon waveguide core and the tapered silicon waveguide core are equal at the connection end face of the constant-width silicon waveguide core and the tapered silicon waveguide core, the compound semiconductor thin film waveguide comprises a first tapered compound semiconductor thin film waveguide, a constant-width compound semiconductor thin film waveguide, and a second tapered compound semiconductor thin film waveguide arranged in series in this order along the extension direction, the width of the first tapered compound semiconductor thin film waveguide gradually widens from one end face side to the other end face side of the cladding, and the width of the constant-width compound semiconductor thin film waveguide is constant along the propagation direction of light from the first tapered compound semiconductor thin film waveguide to the second tapered compound semiconductor thin film waveguide

[0022] The width of the second tapered compound semiconductor thin film waveguide gradually narrows from one end face side to the other end face side of the cladding, the widths of the first tapered compound semiconductor thin film waveguide and the uniform-width compound semiconductor thin film waveguide are equal to each other at the connecting end face of the first tapered compound semiconductor thin film waveguide and the uniform-width compound semiconductor thin film waveguide, the widths of the uniform-width compound semiconductor thin film waveguide and the second tapered compound semiconductor thin film waveguide are equal to each other at the connecting end face of the uniform-width compound semiconductor thin film waveguide and the second tapered compound semiconductor thin film waveguide, the widths of the silicon waveguide core and the compound semiconductor thin film waveguide are equal to each other in a region where the silicon waveguide core and the compound semiconductor thin film waveguide overlap, and the width of the uniform-width compound semiconductor thin film waveguide is 10 μm or more and 20 μm or less.

[0023] According to another preferred embodiment of the optical waveguide element of the present invention, the optical waveguide element further comprises a rib waveguide, a tapered waveguide, and a connecting waveguide, each of which has a ridge portion and a terrace portion. The rib waveguide, the tapered waveguide, the connecting waveguide, and the compound semiconductor thin film waveguide are connected in series in this order, the rib portions of the rib waveguide, the tapered waveguide, and the connecting waveguide have the same thickness, and the terrace portions of the rib waveguide, the tapered waveguide, and the connecting waveguide have the same thickness. The widths of the rib waveguide, the tapered waveguide and the connecting waveguide are equal to one another and constant along the propagation direction, the width of the ridge portion of the rib waveguide is constant along the propagation direction, the width of the ridge portion of the rib waveguide and the tapered waveguide are equal to one another at the connecting end face of the rib waveguide and the tapered waveguide, the width of the ridge portion of the tapered waveguide gradually narrows toward the compound semiconductor thin film waveguide, and the width of the ridge portion of the tapered waveguide and the connecting waveguide are equal to one another at the connecting end face of the tapered waveguide and the connecting waveguide. The width of the ridge portion of the connecting waveguide is constant along the propagation direction, and the widths of the connecting waveguide and the second tapered compound semiconductor thin film waveguide are equal to one another at the connecting end face of the connecting waveguide and the second tapered compound semiconductor thin film waveguide.

[0024] According to another preferred embodiment of the optical waveguide element of the present invention, the compound semiconductor constituting the compound semiconductor thin film waveguide is InP.

[0025] According to another preferred embodiment of the optical waveguide element of the present invention, the compound semiconductor constituting the compound semiconductor thin film waveguide and the terrace portions of the rib waveguide and tapered waveguide is InP, and an active layer of InGaAsP is provided as a quaternary material in the ridge portion of the rib waveguide.

[0026] The method for manufacturing an optical waveguide element of the present invention is a method for manufacturing the above-mentioned optical waveguide element, and includes the steps of: preparing a silicon semiconductor chip having the cladding and the silicon waveguide core; preparing a compound semiconductor chip having the compound semiconductor thin film waveguide; and directly bonding the silicon semiconductor chip and the compound semiconductor chip.

[0027] The method may also include the steps of preparing a silicon semiconductor chip having the cladding and the silicon waveguide core, preparing a compound semiconductor chip having a compound semiconductor thin film, directly bonding the silicon semiconductor chip and the compound semiconductor chip, and patterning the compound semiconductor thin film to obtain the compound semiconductor thin film waveguide. [Effects of the Invention]

[0028] According to the optical waveguide element and its manufacturing method of the present invention, the positional accuracy required when attaching a compound semiconductor waveguide including a light source and the like to a silicon waveguide core can be relaxed to about 2 μm or more. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 2 is a schematic diagram illustrating a first optical waveguide element. [Figure 2] FIG. 4 is a schematic diagram illustrating a second optical waveguide element. [Figure 3] FIG. 10 is a schematic diagram illustrating a third optical waveguide element. [Figure 4] Figure (1) shows the results of the simulation. [Figure 5] Figure (2) shows the results of the simulation. [Figure 6] FIG. 1 is a schematic diagram for explaining a compound semiconductor thin film waveguide having a rib waveguide structure. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the shape, size, and positional relationship of each component are merely shown in a schematic manner to enable understanding of the present invention. Furthermore, preferred configuration examples of the present invention will be described below. However, the materials and numerical conditions of each component are merely preferred examples. Therefore, the present invention is not limited to the following embodiments, and many modifications and variations that can achieve the effects of the present invention can be made without departing from the scope of the configuration of the present invention. Note that, although some hatching is applied in the plan view, it should be understood that this does not represent a cross section, but is added to facilitate understanding of the invention.

[0031] Here, the direction perpendicular to the upper surface of the cladding is defined as the thickness direction, and the direction of light propagation and the thickness direction are defined as the thickness direction. In the following description, the direction perpendicular to both the thickness directions will be referred to as the width direction.

[0032] (First optical waveguide element) An example of the configuration of an optical waveguide element (hereinafter also referred to as a first optical waveguide element) according to a first embodiment of the present invention will be described with reference to Fig. 1. Figs. 1(A) to 1(C) are schematic diagrams for explaining the first optical waveguide element. Fig. 1(A) is a schematic plan view of the first optical waveguide element. Figs. 1(B) and 1(C) are diagrams showing cut end faces of the first optical waveguide element taken along line AA and line BB, respectively.

[0033] The first optical waveguide element is configured to include a silicon semiconductor chip 10 and a compound semiconductor chip 20 provided on the upper surface of the silicon semiconductor chip 10.

[0034] The silicon semiconductor chip 10 comprises a support substrate 100, a cladding 200, and a silicon waveguide core 310. The silicon semiconductor chip 10 can be easily manufactured by a standard silicon photonics manufacturing method, for example, by using a commercially available SOI (Silicon On Insulator) substrate. In this case, the support substrate layer of the SOI substrate, which is formed by sequentially stacking a Si support substrate layer, an SiO2 layer, and a Si layer, serves as the support substrate 100. The SiO2 layer serves as the lower cladding.

[0035] The Si layer is patterned by dry etching or the like to form the silicon waveguide core 310 .

[0036] Thereafter, SiO 2 is deposited on the lower clad by a chemical vapor deposition (CVD) method or the like to form an upper clad. The upper clad is formed so as to cover the silicon waveguide core 310.

[0037] As a result, a silicon waveguide core 310 is obtained that is embedded in the cladding 200 consisting of the lower cladding and the upper cladding, and extends parallel to the upper surface of the cladding 200 .

[0038] The compound semiconductor chip 20 is configured to include a compound semiconductor thin film waveguide 410 .

[0039] The silicon semiconductor chip 10 and the compound semiconductor chip 20 are bonded to the upper surface of the clad 200 so that the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 overlap. Therefore, the compound semiconductor thin film waveguide 410 is formed parallel to the upper surface of the clad 200.

[0040] The silicon semiconductor chip 10 and the compound semiconductor chip 20 are bonded, for example, using CFB (Crystal Film Bonding) technology. In the CFB technology, the silicon semiconductor chip 10 and the compound semiconductor chip 20 are bonded using only the intermolecular force acting between the chips, without using an adhesive or the like.

[0041] The compound semiconductor forming the compound semiconductor thin film waveguide 400 is, for example, InP. The compound semiconductor chip 20 may include a compound semiconductor element such as a laser diode (LD) or a semiconductor optical amplifier (SOA).

[0042] Here, in the region where the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 overlap, one or both of the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 has a width tapered structure in which the width, which is the length in the width direction perpendicular to both the direction perpendicular to the upper surface of the cladding 200 and the direction in which the silicon waveguide core 310 extends, changes along the propagation direction of light.

[0043] Furthermore, it is preferable that the maximum width of either or both of the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 is 7 μm or more. By increasing the width of the waveguide in this manner, restrictions on positional deviation in the width direction can be alleviated in the process of bonding the silicon semiconductor chip 10 and the compound semiconductor chip 20 together.

[0044] In addition, in the region where the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 overlap, the gap between the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 in the direction (thickness direction) perpendicular to the upper surface of the cladding 200, i.e., the thickness of the cladding 200 on the silicon waveguide core 310, is preferably 200 nm or more. This is because if the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 are close to each other in the thickness direction, they will influence each other and cause deformation of the mode field distribution.

[0045] In the first optical waveguide element, the gap between the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 is set to, for example, 400 nm.

[0046] In the first optical waveguide element, a silicon waveguide core 310 is configured to include a first tapered silicon waveguide core 311 and a second tapered silicon waveguide core 312 that are arranged in series in the extension direction.

[0047] The width of the first tapered silicon waveguide core 311 gradually increases from one end face 200a of the cladding 200 toward the second tapered silicon waveguide core 312. On the other hand, the width of the second tapered silicon waveguide core 312 gradually decreases from the first tapered silicon waveguide core 311 toward the other end face 200b of the cladding. At the connection end face between the first tapered silicon waveguide core 311 and the second tapered silicon waveguide core 312, the widths of the first tapered silicon waveguide core 311 and the second tapered silicon waveguide core 312 are equal. In this case, the maximum width of the silicon waveguide core 310 is near the connection end face between the first tapered silicon waveguide core 311 and the second tapered silicon waveguide core 312. This maximum width is preferably 7 μm or more and 14 μm or less, and can be, for example, 7.5 μm. The thickness of the silicon waveguide core 310 may be, for example, 220 nm.

[0048] The width of the first tapered silicon waveguide core 311 at one end face 200a of the cladding 200 can be set to a value suitable for connection to an external silicon optical waveguide circuit. On the other hand, the width of the end of the second tapered silicon waveguide core 312 opposite to the side connected to the first tapered silicon waveguide core 311 can be set to 0 μm or the minimum width that can be produced.

[0049] In the first optical waveguide element, the width of the compound semiconductor thin film waveguide 410 gradually increases from one end face 200a of the cladding 200 toward the other end face 200b. The thickness of the compound semiconductor thin film waveguide 410 can be, for example, 400 nm.

[0050] The width of the compound semiconductor thin film waveguide 410 on one end face 200a side of the cladding 200 can be set to 0 μm or a value within a range of 0.2 to 0.4 μm as the minimum width that can be manufactured. The width of the compound semiconductor thin film waveguide 410 on the other end face 200b side of the cladding 200 can be set to, for example, the same width as the maximum width of the silicon waveguide core 310.

[0051] In the region where the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 overlap, the second tapered silicon waveguide core 312 gradually narrows from its maximum width, for example, 7.5 μm, from one end face 200 a to the other end face 200 b of the cladding 200. Meanwhile, the width of the compound semiconductor thin film waveguide 410 gradually widens to its maximum width, for example, 7.5 μm. Therefore, in this region, there are places where the widths of the silicon waveguide core 310 and the compound semiconductor thin film waveguide 410 are equal.

[0052] The compound semiconductor device can be fabricated by any suitable conventionally known fabrication method, for example, as a rib waveguide having a ridge portion and a terrace portion, and in this case, a tapered waveguide and a connecting waveguide may be provided between the rib waveguide and the compound semiconductor thin film waveguide.

[0053] Here, an example will be described in which the compound semiconductor device is an LD, and the compound semiconductor chip 20 is configured to include a rib waveguide 600, a tapered waveguide 500, a connecting waveguide 700, and a compound semiconductor thin film waveguide 410. When the compound semiconductor device is an LD, a quaternary material such as InGaAsP is used for the active layer of the LD. In this case, the rib waveguide 600, the tapered waveguide 500, the connecting waveguide 700, and the compound semiconductor thin film waveguide 410 are connected in this order.

[0054] The rib waveguide 600 is configured to include a ridge portion 610 and a terrace portion 620. The terrace portions 620 are provided on both sides of the ridge portion 610. The two terrace portions 620 are provided at positions sandwiching the ridge portion 610, and the ridge portion 610 and the two terrace portions 620 extend parallel to each other. The ridge portion 610 is configured by stacking a lower cladding layer 612, an active layer 614, and an upper cladding layer 616 in this order. The lower cladding layer 612 and the upper cladding layer 616 are made of, for example, InP, and the active layer 614 is made of, for example, InGaAsP. Furthermore, the position of the upper surface of the lower cladding layer 612 in the ridge portion 610 is higher than the position of the upper surface of the terrace portions 620.

[0055] The tapered waveguide 500 is configured to include a ridge portion 510 and a terrace portion 520. The cross-sectional shape of the ridge portion 510 of the tapered waveguide 500 is similar to the cross-sectional shape of the ridge portion 610 of the rib waveguide 600, and is configured by laminating a lower cladding layer, an active layer, and an upper cladding layer in this order. The thicknesses of the lower cladding layer, the active layer, and the upper cladding layer are equal to the thicknesses of the lower cladding layer 612, the active layer 614, and the upper cladding layer 616 of the rib waveguide 600, respectively. Furthermore, the materials of the lower cladding layer, the active layer, and the upper cladding layer are equal to the materials of the lower cladding layer 612, the active layer 614, and the upper cladding layer 616 of the rib waveguide 600, respectively, and can be formed using the same process.

[0056] The connecting waveguide 700 is configured to include a ridge portion 710 and a terrace portion 720. The cross-sectional shape of the ridge portion 710 of the connecting waveguide 700 is the same as the cross-sectional shape of the ridge portion 610 of the rib waveguide 600, and is configured by laminating a lower cladding layer, an active layer, and an upper cladding layer in this order. The thicknesses of the lower cladding layer, the active layer, and the upper cladding layer are equal to the thicknesses of the lower cladding layer 612, the active layer 614, and the upper cladding layer 616 of the rib waveguide 600, respectively. Furthermore, the materials of the lower cladding layer, the active layer, and the upper cladding layer are equal to the materials of the lower cladding layer 612, the active layer 614, and the upper cladding layer 616 of the rib waveguide 600, respectively, and can be formed using the same process.

[0057] In this way, the thicknesses of the ridge portions 610 of the rib waveguide 600, the ridge portions 510 of the tapered waveguide 500, and the ridge portions 710 of the connecting waveguide 700 are equal to one another.

[0058] The terrace portion 620 of the rib waveguide 600, the terrace portion 520 of the tapered waveguide 500, the terrace portion 720 of the connecting waveguide 700, and the compound semiconductor thin film waveguide 410 are made of the same compound semiconductor, InP in this case, and have the same thickness.

[0059] The width of the rib waveguide 600 and the width of the ridge portion 610 of the rib waveguide 600 are constant along the propagation direction.

[0060] At the connecting end faces of the rib waveguide 600 and the tapered waveguide 500, the widths of the rib waveguide 600 and the tapered waveguide 500 are equal to each other, and the widths of the ridge portions 610 and 510 of the rib waveguide 600 and the tapered waveguide 500 are equal to each other.

[0061] The width of the tapered waveguide 500 is constant along the propagation direction, while the width of the ridge portion 510 of the tapered waveguide 500 gradually narrows along the propagation direction of light from the rib waveguide 600 toward the coupling waveguide 700.

[0062] At the connecting end faces of the tapered waveguide 600 and the connecting waveguide 700, the tapered waveguide 500 and the connecting waveguide 700 have the same width, and the ridge portion 510 of the tapered waveguide 500 and the ridge portion 710 of the connecting waveguide 700 have the same width.

[0063] The width of the connecting waveguide 700 gradually increases from the tapered waveguide 500 toward the compound semiconductor thin film waveguide 410. On the other hand, the width of the ridge portion 710 of the connecting waveguide 700 is constant along the propagation direction. The length of the ridge portion 710 of the connecting waveguide 700 is shorter than the length of the connecting waveguide 700, and no ridge portion exists at the connection end face between the connecting waveguide 700 and the compound semiconductor thin film waveguide 410, and the compound semiconductor thin film waveguide 410 and the terrace portion 720 of the connecting waveguide 700 are connected.

[0064] By providing the narrow ridge portion 710 in the coupling waveguide 700, it is possible to suppress abrupt changes in the refractive index, and the coupling efficiency from the active layer to the lower cladding layer and the terrace portion is improved.

[0065] Oscillation (laser) light generated in the ridge portion 610 of the rib waveguide 600 propagates from the rib waveguide 600 to the tapered waveguide 500. In the tapered waveguide 500, the width of the ridge portion 510 narrows toward the compound semiconductor thin film waveguide 410, so that the light propagating through the active layer in the ridge portion 510 of the tapered waveguide 500 transfers to the lower cladding layer and terrace portion 520 of the ridge portion 510. The laser light that has transferred to the lower cladding layer and terrace portion 520 passes through the connecting waveguide 700 and is sent to the compound semiconductor thin film waveguide 410, and propagates through the compound semiconductor thin film waveguide 410. The laser light propagating through the compound semiconductor thin film waveguide 410 interferes at the intersection with the silicon waveguide core 310, and transfers to the Si waveguide core 310. The light that has been transferred to the silicon waveguide core 310 propagates through the silicon waveguide core 310 and is extracted to the outside of the silicon semiconductor chip 300 .

[0066] (Second optical waveguide element) An example of the configuration of an optical waveguide element according to a second embodiment of the present invention (hereinafter also referred to as a second optical waveguide element) will be described with reference to Fig. 2. Fig. 2 is a schematic diagram for explaining the second optical waveguide element. Fig. 2(A) is a schematic plan view of the second optical waveguide element, and Fig. 2(B) is a schematic plan view of another example of the configuration of the second optical waveguide element.

[0067] Explanations that overlap with those of the first optical waveguide element may be omitted.

[0068] 2(A), in the second optical waveguide element, the silicon waveguide core 320 has a constant width along the light propagation direction, and it is preferable that the width is 9 μm or more and 20 μm or less. Here, an example in which the width of the silicon waveguide core 320 is 9 μm will be described.

[0069] The compound semiconductor chip 20 is configured to include, for example, a rib waveguide 600, a tapered waveguide 502, and a compound semiconductor thin film waveguide 420. A compound semiconductor element such as an LD is configured in the rib waveguide 600 portion.

[0070] The cross-sectional shapes of the rib waveguide 600 and the tapered waveguide 502 are similar to those of the first optical waveguide element, and therefore a description thereof will be omitted.

[0071] The width of the rib waveguide 600 and the width of the ridge portion 610 of the rib waveguide 600 are constant along the propagation direction.

[0072] At the connecting end faces of the rib waveguide 600 and the tapered waveguide 502, the widths of the rib waveguide 600 and the tapered waveguide 502 are equal to each other, and the widths of the ridge portion 610 of the rib waveguide 600 and the ridge portion 512 of the tapered waveguide 502 are equal to each other.

[0073] The width of the tapered waveguide 502 and the width of the ridge portion 512 of the tapered waveguide 502 gradually decrease along the light propagation direction from the rib waveguide 600 toward the compound semiconductor thin film waveguide 420. The length of the ridge portion 512 of the tapered waveguide 502 is the same as or shorter than the length of the tapered waveguide 502, and the ridge portion 512 does not exist at the connection end face with the compound semiconductor thin film waveguide 420, and the terrace portion 522 of the tapered waveguide 502 and the compound semiconductor thin film waveguide 420 are connected.

[0074] At the connection end face between the tapered waveguide 502 and the compound semiconductor thin film waveguide 420, the widths of the tapered waveguide 502 and the compound semiconductor thin film waveguide 420 are equal to each other.

[0075] The compound semiconductor thin film waveguide 420 gradually narrows from the tapered waveguide 502 side toward one end face 200a of the cladding 200. The compound semiconductor thin film waveguide 420 has a width of, for example, 1.1 μm at the other end face 200b of the cladding 200, a width of, for example, 0.9 μm at the end face 200a of the cladding 200, and a length along the light propagation direction of, for example, 400 μm or more, forming a long tapered structure. The compound semiconductor thin film waveguide 420 has a thickness of, for example, 500 nm.

[0076] Another example of the configuration of the second optical waveguide element will be described with reference to Fig. 2(B), which shows only the silicon waveguide core.

[0077] This other configuration example of the second optical waveguide element differs from the first configuration example of the second optical waveguide element in that a grating whose equivalent refractive index changes periodically along the propagation direction is formed in the silicon waveguide core 321. Other configurations are the same as the first configuration example of the second optical waveguide element, so redundant explanations will be omitted. The silicon waveguide core 321 and the compound semiconductor thin film waveguide 420 are structured so that the equivalent refractive indexes of the light propagating through them are different, and phase matching is achieved by the grating.

[0078] The grating is set so that the phase differs depending on the position in the width direction of the silicon waveguide core 321, causing a decrease in coupling efficiency. The coupling efficiency decreases at the center of the width direction of the silicon waveguide core 321 and increases at the periphery, suppressing changes due to misalignment. The structure, such as making the waveguide longer, is set to allow sufficient light to migrate.

[0079] (Third optical waveguide element) An example of the configuration of an optical waveguide element according to a third embodiment of the present invention (hereinafter also referred to as a third optical waveguide element) will be described with reference to Fig. 3. Fig. 3 is a schematic diagram for explaining the third optical waveguide element. Fig. 3 is a schematic plan view of the third optical waveguide element.

[0080] Explanations that overlap with those of the first optical waveguide element may be omitted.

[0081] In the third optical waveguide element, the silicon waveguide core 330 is configured to include a constant-width silicon waveguide core 331 and a tapered silicon waveguide core 332, which are arranged in series in the extension direction. The tapered silicon waveguide core 332 is located in a region where the silicon waveguide core 330 and the compound semiconductor thin film waveguide 430 overlap.

[0082] The constant-width silicon waveguide core 331 is provided from one end face 200a side of the cladding 200 toward the other end face 200b side, and has a constant width along the light propagation direction.

[0083] On the other hand, the width of the tapered silicon waveguide core 332 gradually narrows from one end face 200a side to the other end face 200b side of the cladding 200. In this case, the width of the tapered silicon waveguide core 332 at the connection end face with the constant-width silicon waveguide core 331 is, for example, 3 μm, and the width of the tapered silicon waveguide core 332 toward the end on the other end face 200b side is, for example, 0.8 μm.

[0084] Furthermore, the widths of the constant-width silicon waveguide core 331 and the tapered silicon waveguide core 332 are equal at the connection end face between the constant-width silicon waveguide core 331 and the tapered silicon waveguide core 332. The thickness of the silicon waveguide core 330 can be, for example, 220 nm.

[0085] The compound semiconductor chip is configured by connecting in series, in this order, a compound semiconductor thin film waveguide 430, a connecting waveguide 703, a tapered waveguide 503, and a rib waveguide 600. The compound semiconductor thin film waveguide 430 also includes a first tapered compound semiconductor thin film waveguide 431, a constant-width compound semiconductor thin film waveguide 432, and a second tapered compound semiconductor thin film waveguide 433, which are arranged in series in the extension direction.

[0086] The compound semiconductor thin film waveguide 430 has a thickness of, for example, 370 nm, and the gap with the silicon waveguide core 330 is 300 nm.

[0087] The width of the first tapered compound semiconductor thin film waveguide 431 gradually increases from one end face 200a of the cladding 200 toward the constant-width compound semiconductor thin film waveguide 432. At the connection end face between the first compound semiconductor thin film waveguide 431 and the constant-width compound semiconductor thin film waveguide 432, the width of the first compound semiconductor thin film waveguide 431 and the width of the constant-width compound semiconductor thin film waveguide 432 are equal to each other.

[0088] The constant-width compound semiconductor thin film waveguide 432 has a constant width along the propagation direction of light from the first tapered compound semiconductor thin film waveguide 431 to the second tapered compound semiconductor thin film waveguide 433 .

[0089] The width of the second tapered compound semiconductor thin film waveguide 433 gradually narrows from the constant-width compound semiconductor thin film waveguide 432 toward the other end face of the cladding 200. At the connection end face between the constant-width compound semiconductor thin film waveguide 432 and the second tapered compound semiconductor thin film waveguide 433, the width of the constant-width compound semiconductor thin film waveguide 432 and the width of the second tapered compound semiconductor thin film waveguide 433 are equal to each other.

[0090] The width of the equal-width compound semiconductor thin film waveguide 432 is preferably 10 to 20 μm, and can be set to, for example, 10 μm. The width of the first tapered compound semiconductor thin film waveguide 431 on the one end face 200a side of the cladding 200 is, for example, 1 μm.

[0091] The rib waveguide 600 is configured to include a ridge portion 610 and a terrace portion 620. The terrace portions 620 are provided on both sides of the ridge portion 610. The two terrace portions 620 are provided at positions sandwiching the ridge portion 610, and the ridge portion 610 and the two terrace portions 620 extend parallel to each other. The ridge portion 610 is configured by stacking a lower cladding layer 612, an active layer 614, and an upper cladding layer 616 in this order. The lower cladding layer 612 and the upper cladding layer 616 are made of, for example, InP, and the active layer 614 is made of, for example, InGaAsP. Furthermore, the position of the upper surface of the lower cladding layer 612 in the ridge portion 610 is higher than the position of the upper surface of the terrace portions 620.

[0092] The tapered waveguide 503 is configured to include a ridge portion 513 and a terrace portion 523. The cross-sectional shape of the ridge portion 513 of the tapered waveguide 503 is similar to the cross-sectional shape of the ridge portion 610 of the rib waveguide 600, and is configured by laminating a lower cladding layer, an active layer, and an upper cladding layer in this order. The thicknesses of the lower cladding layer, the active layer, and the upper cladding layer are equal to the thicknesses of the lower cladding layer 612, the active layer 614, and the upper cladding layer 616 of the rib waveguide 600, respectively.

[0093] The connecting waveguide 703 is configured to include a ridge portion 713 and a terrace portion 723. The cross-sectional shape of the ridge portion 713 of the connecting waveguide 703 is the same as the cross-sectional shape of the ridge portion 610 of the rib waveguide 600, and is configured by laminating a lower cladding layer, an active layer, and an upper cladding layer in this order. The thicknesses of the lower cladding layer, the active layer, and the upper cladding layer are equal to the thicknesses of the lower cladding layer 612, the active layer 614, and the upper cladding layer 616 of the rib waveguide 600, respectively.

[0094] In this way, the thicknesses of the ridge portion 610 of the rib waveguide 600, the ridge portion 513 of the tapered waveguide 503, and the ridge portion 713 of the connecting waveguide 703 are equal to one another. Note that the ridge portion 713 of the connecting waveguide 703 may extend into the second tapered compound semiconductor thin film waveguide 433.

[0095] The terrace portion 620 of the rib waveguide 600, the terrace portion 523 of the tapered waveguide 503, the terrace portion 723 of the connecting waveguide 703, and the compound semiconductor thin film waveguide 430 are made of the same compound semiconductor, InP in this case, and have the same thickness.

[0096] (Design conditions) A simulation obtained using a three-dimensional BPM (Beam Propagation Method) method will be described with reference to Figures 4 and 5. Figures 4 and 5 are diagrams showing the results of the simulation.

[0097] 4A to 4C are diagrams showing the magnitude of fundamental mode output versus the difference in widthwise misalignment between the silicon semiconductor chip 10 and the compound semiconductor chip 20 when they are bonded together.

[0098] FIG. 5 summarizes the characteristics of each embodiment.

[0099] 4A to 4C, the horizontal axis represents the widthwise offset (axial offset) of the silicon waveguide core (unit: μm), and the vertical axis represents the fundamental mode output. Here, the fundamental mode output represents the proportion of laser light generated in the active layer 614 of the rib waveguide 600 that is output via the silicon waveguide core.

[0100] 4A to 4C correspond to the first to third embodiments, respectively. In the first embodiment, the gap between the silicon waveguide core and the compound semiconductor thin film waveguide is set to 400 nm, and the lengths (taper lengths) of the second tapered silicon waveguide core and the compound semiconductor thin film waveguide are changed.

[0101] As shown in FIG. 4A, when comparing taper lengths of 200 μm, 400 μm, and 800 μm, it can be seen that the longer the taper length, the greater the deviation tolerance.

[0102] In this example, the width of the ridges of the rib waveguide is 2 μm, the thickness of the active layer is 500 nm, the width of the rib waveguide is 4 μm, the maximum width of the silicon waveguide core and compound semiconductor thin film waveguide is 7.5 μm, and the width of the tip of the tapered structure is 0.2 μm.

[0103] 4(B), the silicon waveguide core has a width of 9 μm and a thickness of 220 nm, and the InP compound semiconductor thin film waveguide has a 400 μm long taper with a width ranging from 1.1 to 0.9 μm, a thickness of 500 nm, and a gap of 300 nm.

[0104] In the third embodiment shown in Figure 4(C), the tapered silicon waveguide core of the silicon waveguide core narrows in width from 3 µm to 0.8 µm and has a long taper of 400 µm in length. The silicon waveguide core has a thickness of 220 nm, the InP compound semiconductor thin film waveguide has a fixed-width compound semiconductor thin film waveguide with a width of 10 µm, a length of 200 µm, a thickness of 370 nm, and a length of 150 µm and a tip width of 1 µm. The gap is 300 nm.

[0105] In all of the first to third embodiments, the reduction rate is about 1 dB, which is acceptable for axis misalignment up to about 2 μm. Figure 4(A) shows the results of changing the taper length L when the gap is set to 400 nm in the first embodiment, and the longer the taper length L, the greater the misalignment tolerance.

[0106] 5, in all of the first to third embodiments, the maximum transmittance is 95% or more, and a positional deviation of up to about 2 μm is tolerable. The required processing accuracy is about ±5% for thickness and about 100 μm for width, and when attaching a compound semiconductor waveguide including a light source to a silicon waveguide core, the positional accuracy is relaxed to about 2 μm or more, which is practical.

[0107] Although the compound semiconductor thin film waveguides 400 to 402 included in the first to third optical waveguide elements are wire-type in the above example, the present invention is not limited to this. The compound semiconductor thin film waveguides may have a rib waveguide structure having ridge portions and terrace portions.

[0108] Fig. 6 is a schematic diagram for explaining a compound semiconductor thin film waveguide with a rib waveguide structure, and shows a cut end surface of the compound semiconductor thin film waveguide with a rib waveguide structure of a second optical waveguide element.

[0109] 2 serves as the ridge portion, and on both sides of the ridge portion are provided 200 nm thick InP layers as terrace portions 425. The terrace portions 425 function as supports for the ridge portion 420, which is more preferable because it increases the strength.

[0110] Here, an example has been described in which the compound semiconductor thin film waveguide of the second optical waveguide element has a rib waveguide structure. However, the compound semiconductor thin film waveguide of the first and third optical waveguide elements may also have a rib waveguide structure. It can be structured. [Explanation of symbols]

[0111] 10 Silicon semiconductor chip 20 Compound semiconductor chips 100 Support substrate 200 Clad 310, 320, 330 Silicon waveguide core 311, 312, 332 Tapered silicon waveguide core 331 Equal-width silicon waveguide core 410, 420, 430 Compound semiconductor thin film waveguide 431, 433 Tapered compound semiconductor thin film waveguide 432 Equivalent-Width Compound Semiconductor Thin-Film Waveguides 425, 520, 620, 720 Terrace area 500, 502, 503 Tapered waveguide 510, 512, 610, 710 ridge part 600 Rib Waveguide 612 Lower cladding layer 614 Active layer 616 Upper cladding layer 700, 703 Connected waveguide

Claims

1. Clad and a silicon waveguide core embedded within the cladding and extending parallel to an upper surface of the cladding; a compound semiconductor thin film waveguide extending parallel to the upper surface of the clad on the upper surface of the clad above the silicon waveguide core; Equipped with In a region where the silicon waveguide core and the compound semiconductor thin film waveguide overlap, one or both of the silicon waveguide core and the compound semiconductor thin film waveguide is provided with a width tapered structure in which a width, which is a length in a width direction perpendicular to both a thickness direction perpendicular to an upper surface of the cladding and a direction in which the silicon waveguide core extends, changes along a propagation direction of light, The maximum width of either or both of the silicon waveguide core and the compound semiconductor thin film waveguide is 7 μm or more. Optical waveguide element.

2. The distance between the silicon waveguide core and the compound semiconductor thin film waveguide in a direction perpendicular to the upper surface of the cladding is 200 nm or more. The optical waveguide element according to claim 1 .

3. the silicon waveguide core includes a first tapered silicon waveguide core and a second tapered silicon waveguide core that are provided in series from one end face side of the clad in an extension direction, the first tapered silicon waveguide core has a width that gradually increases from one end face side of the cladding toward the second tapered silicon waveguide core, the second tapered silicon waveguide core has a width that gradually narrows from the first tapered silicon waveguide core toward the other end face of the cladding, the compound semiconductor thin film waveguide has a width that gradually increases from one end face side of the cladding to the other end face side, in a region where the second tapered silicon waveguide core and the compound semiconductor thin film waveguide overlap, there is a location where a width of the second tapered silicon waveguide core and a width of the compound semiconductor thin film waveguide are equal to each other; The maximum width of the second tapered silicon waveguide core and the compound semiconductor thin film waveguide is 7 μm or more and 14 μm or less. The optical waveguide element according to claim 1 .

4. The optical waveguide further includes a rib waveguide, a tapered waveguide, and a connecting waveguide, each of which has a ridge portion and a terrace portion; the rib waveguide, the tapered waveguide, the connecting waveguide, and the compound semiconductor thin film waveguide are connected in this order; the thicknesses of the rib waveguide, the tapered waveguide, and the ridge portions of the connecting waveguide are equal to one another; the thickness of the terrace portions of the rib waveguide, the tapered waveguide, and the connecting waveguide is equal to the thickness of the compound semiconductor thin film waveguide; the width of the rib waveguide is constant along the propagation direction; the width of the rib portion of the rib waveguide is constant along the propagation direction; the width of the tapered waveguide is constant along the propagation direction and equal to the width of the rib waveguide; a width of the ridge portion of the tapered waveguide gradually narrows toward the connecting waveguide, At the connection end faces of the rib waveguide and the tapered waveguide, the widths of the ridge portions of the rib waveguide and the tapered waveguide are equal to each other; the width of the coupling waveguide gradually increases toward the compound semiconductor waveguide; the ridge portion of the connecting waveguide has a constant width along the propagation direction, and is provided with a length from an end of the connecting waveguide on the tapered waveguide side that is shorter than the length of the connecting waveguide along the propagation direction, At the connection end faces of the tapered waveguide and the connecting waveguide, the widths of the tapered waveguide and the connecting waveguide are equal to each other, and the widths of the ridge portions of the tapered waveguide and the connecting waveguide are equal to each other. At the connection end faces of the connecting waveguide and the compound semiconductor thin film waveguide, the widths of the connecting waveguide and the compound semiconductor thin film waveguide are equal to each other. The optical waveguide element according to claim 3 .

5. The optical waveguide further includes a rib waveguide and a tapered waveguide, each of which includes a ridge portion and a terrace portion; the rib waveguide, the tapered waveguide, and the compound semiconductor thin film waveguide are connected in series in this order; the thicknesses of the rib waveguide and the ridge portions of the tapered waveguide are equal to each other; the thickness of the terrace portion of the rib waveguide and the tapered waveguide is equal to the thickness of the compound semiconductor thin film waveguide; the width of the rib waveguide is constant along the propagation direction; the width of the rib portion of the rib waveguide is constant along the propagation direction; At the connection end faces of the rib waveguide and the tapered waveguide, the widths of the rib waveguide and the tapered waveguide are equal to each other, and the widths of the ridge portions of the rib waveguide and the tapered waveguide are equal to each other; a width of the tapered waveguide and a width of a ridge portion of the tapered waveguide gradually narrow toward the compound semiconductor thin film waveguide; the widths of the tapered waveguide and the compound semiconductor thin film waveguide are equal to each other at the connection end faces of the tapered waveguide and the compound semiconductor thin film waveguide; the width of the compound semiconductor thin film waveguide gradually narrows as it moves away from the tapered waveguide along the propagation direction; the width of the silicon waveguide core is constant along the propagation direction; The width of the silicon waveguide core is 9 μm or more and 20 μm or less. The optical waveguide element according to claim 1 .

6. The silicon waveguide core has a grating formed therein, the equivalent refractive index of which changes periodically along the propagation direction. The optical waveguide element according to claim 5 .

7. The grating has a phase or a period that varies depending on the position in the width direction of the silicon waveguide core. The optical waveguide element according to claim 6 .

8. the silicon waveguide core includes a constant-width silicon waveguide core and a tapered silicon waveguide core, which are arranged in series in this order in the extending direction; the width of the constant-width silicon waveguide core is constant along the propagation direction; the width of the tapered silicon waveguide core gradually narrows from the constant-width silicon waveguide core toward the other end face of the cladding; the widths of the constant-width silicon waveguide core and the tapered silicon waveguide core are equal to each other at the connection end faces of the constant-width silicon waveguide core and the tapered silicon waveguide core, the compound semiconductor thin film waveguide comprises a first tapered compound semiconductor thin film waveguide, a constant-width compound semiconductor thin film waveguide, and a second tapered compound semiconductor thin film waveguide, which are arranged in series in this order in an extending direction; the first tapered compound semiconductor thin film waveguide has a width that gradually increases from one end face side of the cladding to the other end face side, the constant-width compound semiconductor thin film waveguide has a constant width along a propagation direction of light from the first tapered compound semiconductor thin film waveguide to the second tapered compound semiconductor thin film waveguide, the second tapered compound semiconductor thin film waveguide has a width that gradually narrows from one end face side of the cladding to the other end face side, the widths of the first tapered compound semiconductor thin film waveguide and the equal-width compound semiconductor thin film waveguide are equal to each other at the connection end faces of the first tapered compound semiconductor thin film waveguide and the equal-width compound semiconductor thin film waveguide; At a connection end face of the equal-width compound semiconductor thin film waveguide and the second tapered compound semiconductor thin film waveguide, the widths of the equal-width compound semiconductor thin film waveguide and the second tapered compound semiconductor thin film waveguide are equal to each other, in a region where the silicon waveguide core and the compound semiconductor thin film waveguide overlap, there is a location where the width of the silicon waveguide core and the width of the compound semiconductor thin film waveguide are equal; The width of the equal-width compound semiconductor thin film waveguide is 10 μm or more and 20 μm or less. The optical waveguide element according to claim 1 .

9. The optical waveguide further includes a rib waveguide, a tapered waveguide, and a connecting waveguide, each of which has a ridge portion and a terrace portion; the rib waveguide, the tapered waveguide, the connecting waveguide, and the compound semiconductor thin film waveguide are connected in series in this order; the thicknesses of the rib waveguide, the tapered waveguide, and the ridge portions of the connecting waveguide are equal to one another; the thickness of the terrace portions of the rib waveguide, the tapered waveguide, and the connecting waveguide is equal to the thickness of the compound semiconductor thin film waveguide; the widths of the rib waveguide, the tapered waveguide, and the connecting waveguide are equal to each other and constant along the propagation direction; the width of the rib portion of the rib waveguide is constant along the propagation direction; At the connection end faces of the rib waveguide and the tapered waveguide, the widths of the ridge portions of the rib waveguide and the tapered waveguide are equal to each other; In the tapered waveguide, the width of the ridge portion gradually narrows toward the compound semiconductor thin film waveguide, At the connection end faces of the tapered waveguide and the connecting waveguide, the widths of the ridge portions of the tapered waveguide and the connecting waveguide are equal to each other; a width of the ridge portion of the connecting waveguide is constant along the propagation direction; At a connection end face between the connecting waveguide and the second tapered compound semiconductor thin film waveguide, the widths of the connecting waveguide and the second tapered compound semiconductor thin film waveguide are equal to each other. The optical waveguide element according to claim 8 .

10. The compound semiconductor constituting the compound semiconductor thin film waveguide is InP. The optical waveguide element according to any one of claims 1 to 3 and 8.

11. the compound semiconductor constituting the compound semiconductor thin film waveguide and the terrace portions of the rib waveguide and the tapered waveguide is InP; The rib waveguide has an active layer made of InGaAsP as a quaternary material. The optical waveguide element according to any one of claims 4 to 7 and 9.

12. A method for producing the optical waveguide element according to any one of claims 1 to 9, comprising: providing a silicon semiconductor chip having the cladding and the silicon waveguide core; preparing a compound semiconductor chip having the compound semiconductor thin film waveguide; a step of directly bonding the silicon semiconductor chip and the compound semiconductor chip; A method for manufacturing an optical waveguide element comprising:

13. A method for producing the optical waveguide element according to any one of claims 1 to 9, comprising: providing a silicon semiconductor chip having the cladding and the silicon waveguide core; providing a compound semiconductor chip having a compound semiconductor thin film; a step of directly bonding the silicon semiconductor chip and the compound semiconductor chip; a step of patterning the compound semiconductor thin film to obtain the compound semiconductor thin film waveguide; A method for manufacturing an optical waveguide element comprising:

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