Optical waveguide core, optical waveguide, light-emitting module, and electronic device

Abstract

An optical waveguide core according to the present disclosure contains a compound. The atomic composition percentages of each of Si, O, and N measured by X-ray photoelectron spectroscopy of the compound are in the ranges of 34.0-60.0 at% Si, 1.0-65.0 at% O, and 1.0-50.0 at% N. In the infrared absorption spectrum measured by Fourier transform infrared spectroscopy of the compound, formula (a) ν1 > ν2 is satisfied, where ν1 is the peak intensity derived from the stretching vibration of N-H bonds, and ν2 is the peak intensity derived from the stretching vibration of Si-H bonds.

Description

Optical waveguide core, optical waveguide, light-emitting module and electronic device

[0001] The present disclosure relates to a core of an optical waveguide, an optical waveguide, a light-emitting module, and an electronic device.

[0002] Optical waveguides are known as transmission paths used in optical communications. An optical waveguide includes a core, which is an optical path, and a cladding surrounding the core. International Publication No. 2023 / 136349 and Japanese Patent Application Laid-Open No. 2016-156933 disclose optical waveguides containing silicon oxynitride in the core.

[0003] (1) The core of the optical waveguide of the present disclosure contains compound A1. Compound A1 has atomic composition percentages of Si, O, and N measured by X-ray photoelectron spectroscopy as follows: Si: in the range of 34.0 to 60.0 at %, O: in the range of 1.0 to 65.0 at %, and N: in the range of 1.0 to 50.0 at %. Compound A1 satisfies the following formula (a) when the peak intensity due to the stretching vibration of the N-H bond is v1 and the peak intensity due to the stretching vibration of the Si-H bond is v2 in the infrared absorption spectrum measured by Fourier transform infrared spectroscopy: Formula (a) v1>v2

[0004] (2) The core of the optical waveguide of the present disclosure contains compound A2. Compound A2 satisfies the following formulas (1) and (2) when the atomic composition ratio of Si, O, and N measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y: Formula (1): 0<x<2 In an infrared absorption spectrum measured by Fourier transform infrared spectroscopy, Compound A2 satisfies the following formula (a), where v1 is the peak intensity due to the stretching vibration of the N—H bond and v2 is the peak intensity due to the stretching vibration of the Si—H bond. Formula (a) v1>v2

[0005] (3) The core of the optical waveguide according to (1) or (2) above contains compound A1 or A2. In the infrared absorption spectrum of compound A1 or A2 measured by Fourier transform infrared spectroscopy, when the peak intensity due to the stretching vibration of the Si—O bond is v3 and the peak intensity due to the stretching vibration of the Si—N bond is v4, at least one of the following formulas (b) and (c) is satisfied: Formula (b) v1<v3 Formula (c) v1<v4

[0006] (4) The core of the optical waveguide according to any one of (1) to (3) above contains compound A1 or A2. In the infrared absorption spectrum of compound A1 or A2 measured by Fourier transform infrared spectroscopy, the larger of the peak intensity v3 due to the stretching vibration of the Si—O bond and the peak intensity v4 due to the stretching vibration of the Si—N bond is defined as v ｍａｘ When this is the case, the following formula (d) is satisfied. Formula (d) ν2 / ν ｍａｘ ≧0.001

[0007] (5) The core of the optical waveguide according to (4) above contains compound A1 or A2. In the infrared absorption spectrum of compound A1 or A2 measured by Fourier transform infrared spectroscopy, the larger of the peak intensity v3 due to the stretching vibration of the Si—O bond and the peak intensity v4 due to the stretching vibration of the Si—N bond is defined as v ｍａｘ When this is the case, the following formula (e) is satisfied: ｍａｘ ≦0.060

[0008] (6) The core of the optical waveguide according to any one of (1) to (5) above contains compound A1 or A2. In the infrared absorption spectrum of compound A1 or A2 measured by Fourier transform infrared spectroscopy, the larger of the peak intensity v3 due to the stretching vibration of the Si—O bond and the peak intensity v4 due to the stretching vibration of the Si—N bond is defined as v ｍａｘ When this is the case, the following formula (f) is satisfied. Formula (f) ν1 / ν ｍａｘ ≧0.300

[0009] (7) The core of the optical waveguide according to any one of (1) to (6) above contains compound A1 or A2. In the infrared absorption spectrum of compound A1 or A2 measured by Fourier transform infrared spectroscopy, the following formula (g) is satisfied: v2 / v1≦0.20.

[0010] (8) The core of the optical waveguide according to any one of (1) to (7) above contains compound A1 or A2. When the peak intensity due to the deformation vibration of the N-H bond in the infrared absorption spectrum of compound A1 or A2 measured by Fourier transform infrared spectroscopy is v5, the following formula (h) is satisfied: v1>v5

[0011] (9) The core of the optical waveguide according to any one of (1) to (8) above contains compound A1 or A2. The refractive index of compound A1 or A2 is in the range of 1.5 to 2.1. The Young's modulus of compound A1 or A2 is in the range of 50 to 150 GPa.

[0012] (10) The core of the optical waveguide according to any one of (1) to (9) above contains compound A1 or A2, which satisfies the following formula (3) when the atomic composition ratio of Si, O, and N in compound A1 or A2 measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y:

[0013] (11) The core of the optical waveguide according to any one of (1) to (10) above contains compound A1 or A2. When the atomic composition ratio of Si, O, and N in compound A1 or A2 measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y, the following formula (4) is satisfied: y≧−0.39x+0.79

[0014] (12) The core of the optical waveguide according to any one of (1) to (11) above contains compound A1 or A2. When the atomic composition ratio of Si, O, and N in compound A1 or A2 measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y, the following formula (5) is satisfied: y≦0.9.

[0015] (13) The core of the optical waveguide according to any one of (1) to (12) above contains compound A1 or A2. The apparent density of compound A1 or A2 is 2.1 g / cm ３ That's all.

[0016] (14) The core of the optical waveguide according to any one of (1) to (13) above contains compound A1 or A2, which has a Young's modulus of 120 GPa or less.

[0017] (15) The core of the optical waveguide according to any one of (1) to (14) above contains compound A1 or A2, which has a Young's modulus of 60 GPa or more.

[0018] (16) The core of the optical waveguide according to any one of (1) to (15) above contains compound A1 or A2, which has a refractive index in the range of 1.55 to 1.80.

[0019] (17) An optical waveguide according to the present disclosure includes: a core of the optical waveguide according to any one of (1) to (16) above; and a clad surrounding the core, the clad being made of SiO ２ Contains as the main component.

[0020] (18) In the optical waveguide described in (17) above, when the thickness of the core is 4 μm, the width is 5 μm, and the length is 2.5 mm, the transmittance of light with a wavelength of 450 nm is 55% or more.

[0021] (19) A light-emitting module according to the present disclosure includes an optical waveguide module and a light-emitting element, and the optical waveguide module includes the optical waveguide according to (17) or (18) above, a substrate, and an electrode.

[0022] (20) An electronic device according to the present disclosure includes the light-emitting module according to (19) above.

[0023] According to the present disclosure, it is possible to provide a core of an optical waveguide with improved transmission efficiency, an optical waveguide with improved optical transmission efficiency, and the like.

[0024] 1 is a perspective view of an optical waveguide 1 according to an embodiment of the present invention; FIG. 2 is a perspective view of a light-emitting module 100 including the optical waveguide 1 according to an embodiment of the present invention; FIG. 3 is a perspective view of a light-emitting module 100 including the optical waveguide 1 according to an embodiment of the present invention; ３ N ４ ) is a diagram showing the molecular structure of silicon oxide (SiO ２ 1 is an image of the molecular structure of a silicon oxynitride having a defect structure. 2 is an image of the molecular structure of a silicon oxynitride having a defect structure. 3 is an example of infrared absorption spectra of compounds A11 to A13 measured by Fourier transform infrared spectroscopy. 4 is a graph showing the relationship between x and y when the atomic composition ratio of Si, O, and N is Si:O:N=1:x:y. 5 is a cross-sectional view of an example of an optical waveguide 1 according to the present embodiment. 6 is an explanatory diagram of the numerical aperture (NA) in the optical waveguide 1. 7 is a graph showing the relationship between the numerical aperture (NA) and the light-receiving angle range 2θ [°]. 8 is a graph plotting the relationship between x and y when the atomic composition ratio of Si, O, and N is Si:O:N=1:x:y, and Experimental Examples 1 to 17. 9 is an infrared absorption spectrum of Experimental Examples 1 to 3 measured by Fourier transform infrared spectroscopy. 10 is an infrared absorption spectrum of Experimental Examples 4 to 6 measured by Fourier transform infrared spectroscopy. 1 shows infrared absorption spectra measured by Fourier transform infrared spectroscopy for Experimental Examples 7 to 9. 1 shows infrared absorption spectra measured by Fourier transform infrared spectroscopy for Experimental Examples 10 to 12. 1 shows infrared absorption spectra measured by Fourier transform infrared spectroscopy for Experimental Examples 13 to 15. 1 shows infrared absorption spectra measured by Fourier transform infrared spectroscopy for Experimental Example 16. 1 shows infrared absorption spectra measured by Fourier transform infrared spectroscopy for Experimental Example 17.

[0025] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​written before and after "to" as the lower and upper limits.

[0026] 1 is a perspective view of an optical waveguide 1 according to this embodiment. The optical waveguide 1 includes a clad 2 and a core 3. The clad 2 may surround the core 3. However, the present disclosure is not limited to this.

[0027] 2 is an overall perspective view of a light emitting module 100 having the optical waveguide 1 of this embodiment. The light emitting module 100 includes an optical waveguide module 10, a lens 20, a light emitting element 30, a lid 40, and the like.

[0028] The mechanism of manifestation or action of the effects of the present disclosure is presumed to be as follows.

[0029] One method for improving the optical transmission efficiency of an optical waveguide is to improve the transmission efficiency of the core. The transmission efficiency of the core, i.e., the transmittance of the compound contained in the core, can be improved by reducing the light absorption by the compound. The light absorption by the compound can be reduced by reducing the defect structure or the bonds between specific atoms in the compound.

[0030] On the other hand, optical waveguides have appropriate flexibility so that they can be conformed to the shape of the light-emitting module or electronic device in which they are mounted, thereby reducing warping and cracking of the optical waveguide caused by the application of external force when the optical waveguide is mounted. In compounds with an appropriate defect structure, atoms move in a gliding manner, thereby dispersing stress caused by the application of external force. This allows a core containing the compound to have appropriate flexibility. An example of an index indicating flexibility is Young's modulus, and in compounds with an appropriate defect structure, the Young's modulus can be relatively reduced. Furthermore, the difference in Young's modulus between the core and the cladding surrounding the core is relatively small. This reduces warping and cracking of the core caused by the fabrication of the optical waveguide.

[0031] The compounds according to the present disclosure have a relatively small number of bonds between specific atoms and a moderately defective structure, which is believed to enable them to be used as core materials for optical waveguides and to improve the optical transmission efficiency of the optical waveguides.

[0032] <<Core of Optical Waveguide>> Hereinafter, the compound A contained in the core of the optical waveguide of the present disclosure will be described in order from the first to second embodiments. Note that the compound A in the first embodiment will be described as compound A1, and the compound A in the second embodiment will be described as compound A2. The core of the optical waveguide of the present disclosure may contain only the compound A, or may further contain components other than the compound A. The volume content of the compound A relative to the total volume of the optical waveguide core may be 95% or more, or even 99% or more. The core of the optical waveguide may contain a material for a conventionally known optical waveguide core, as long as the effects of the present disclosure are obtained. Furthermore, the core of the optical waveguide may contain, in addition to the compound A, impurities unavoidable in manufacturing, as long as the effects of the present disclosure are obtained.

[0033] First Embodiment In the first embodiment, the core of the optical waveguide contains compound A1. The atomic composition percentages of Si, O, and N of compound A1 measured by X-ray photoelectron spectroscopy are Si: in the range of 34.0 to 60.0 at %, O: in the range of 1.0 to 65.0 at %, and N: in the range of 1.0 to 50.0 at %. In the infrared absorption spectrum of compound A1 measured by Fourier transform infrared spectroscopy, when the peak intensity due to the stretching vibration of the N—H bond is defined as v1 and the peak intensity due to the stretching vibration of the Si—H bond is defined as v2, the following formula (a) is satisfied: Formula (a) v1>v2

[0034] Compound A1 contains at least a Si (silicon) atom, an O (oxygen) atom, an N (nitrogen) atom, and an H (hydrogen) atom. Compound A1 may contain other atoms as long as the effects of the present disclosure are achieved.

[0035] [Atomic Composition Percentage] In the present disclosure, the term "atomic composition percentage" refers to the ratio of the number of a specific atom to the total number of all atoms contained in compound A1. The atomic composition percentages of Si, O, and N contained in compound A1 can be measured by X-ray photoelectron spectroscopy (XPS) and fall within the above ranges.

[0036] (Measurement Method) Measurement by X-ray photoelectron spectroscopy (XPS) is performed by the following method and conditions. As a sample of compound A1, a thin film of compound A1 is formed on a substrate. The thickness of the thin film is in the range of 2 to 5 μm. The shape of the substrate is not particularly limited. An example of the substrate may be a Si substrate with a thickness in the range of 0.5 to 0.6 mm, a width in the range of 5 to 15 mm, and a length in the range of 5 to 15 mm. As the measurement device, for example, an X-ray photoelectron spectroscopy device "PHI Quantera II" (manufactured by ULVAC-PHI Corporation) may be used. The measurement conditions are not particularly limited. An example of the measurement conditions may be as follows. AlKα rays are used as the X-ray source, and the X-ray irradiation conditions are a beam diameter of 100 μm, an acceleration voltage of 15 kV, and a measurement area in a range of 100 μm in diameter. The detector conditions are a pass energy of 224 eV and a step size of 0.4 eV. Ar sputtering is performed at an acceleration voltage of 4 kV. The depth conversion is based on SiO ２ An etching rate of 6.72 nm / min is applied.

[0037] The photoelectron spectrum obtained by X-ray photoelectron spectroscopy shows the binding energy of the measured electrons to the atomic nucleus on the horizontal axis and the intensity of the emitted photoelectrons on the vertical axis. The binding energy value depends on the type of atom, the electronic state of the atom, etc., so the composition of a material can be analyzed from the binding energy value.

[0038] The atomic composition percentage of Si may be in the range of 34.0 to 60.0 at%, or better, in the range of 41.0 to 47.0 at%, the atomic composition percentage of O may be in the range of 1.0 to 65.0 at%, or better, in the range of 21.0 to 28.0 at%, and the atomic composition percentage of N may be in the range of 1.0 to 50.0 at%, or better, in the range of 29.0 to 34.0 at%.

[0039] [Relationship of Peak Intensities in Infrared Absorption Spectrum] In an infrared absorption spectrum measured by Fourier Transform Infrared Spectroscopy (FTIR), the molecular structure of compound A1 can be inferred from the relationship between peak intensities resulting from bonds of various atoms. Furthermore, whether compound A1 contains an H (hydrogen) atom can be determined from the relationship between peak intensities resulting from bonds of various atoms including an H (hydrogen) atom.

[0040] FIG. 3 shows the structure of silicon nitride (Si ３ N ４ As shown in Figure 3, in the molecular structure of silicon nitride without a defect structure, most of the Si atoms are bonded to N atoms, and bonds between Si atoms are rarely observed.

[0041] FIG. 4 shows the structure of silicon oxide (SiO ２ As shown in Figure 4, even in the molecular structure of silicon oxide without a defect structure, many of the Si atoms are bonded to O atoms, and bonds between Si atoms are rarely observed.

[0042] Fig. 5 is an image of the molecular structure of silicon oxynitride without defect structures 5. As shown in Fig. 5, even in silicon oxynitride without defect structures 5, most of the Si atoms are bonded to N atoms or O atoms, and bonds between Si atoms are rarely observed.

[0043] Figure 6 is an image of the molecular structure of silicon oxynitride having a defect structure, i.e., compound A1. As shown in Figure 6, bonds between Si atoms are observed in compound A1. Since the defect structure and bonds between Si atoms absorb visible light, reducing these can improve the transmittance of compound A1. Note that, hereinafter, bonds between Si atoms will also be referred to as "Si-Si bonds."

[0044] 6, compound A1 contains a trace amount of H atoms, which is thought to result in a moderate defect structure. Therefore, in the molecular structure of compound A1, there are bonds between Si atoms and H atoms, bonds between O atoms and H atoms, and bonds between N atoms and H atoms, albeit in trace amounts. Note that hereinafter, a bond between a Si atom and an H atom will also be referred to as an "Si-H bond," a bond between an O atom and an H atom as an "O-H bond," and a bond between an N atom and an H atom as an "N-H bond."

[0045] In Fourier transform infrared spectroscopy, compound A1 is irradiated with infrared light and the amount of transmitted or reflected light is measured. The infrared light is absorbed as energy of the vibrational or rotational motion of molecular bonds, and information on the molecular structure can be obtained from the measured infrared absorption spectrum.

[0046] Infrared light is absorbed when the dipole moment changes due to vibration of molecular bonds. Generally, in the case of linear molecules, the dipole moment does not change during symmetric stretching vibrations, so with some exceptions, infrared light is not absorbed. However, in some exceptional cases, such as carbon dioxide, antisymmetric stretching vibrations occur, causing a change in the dipole moment, resulting in infrared light absorption. O, which is a linear molecule, ２ , N ２ , Si ２ In diatomic molecules such as (I) and (II), antisymmetric stretching vibrations do not occur, and therefore infrared light absorption does not occur, making it difficult to directly detect each bond state by Fourier transform infrared spectroscopy. Furthermore, Si-Si bonds do not absorb infrared light, making it difficult to detect them by measurement methods using infrared light. In other words, it is relatively difficult to adequately observe Si-Si bonds by Fourier transform infrared spectroscopy. Therefore, in the first embodiment, Si-H bonds and N-H bonds are observed by Fourier transform infrared spectroscopy, and the molecular structure of compound A1 is inferred from the relationship between the peak intensities derived from these bonds.

[0047] It is believed that Si-Si bonds are formed when dangling bonds occur in Si atoms due to a lack of O atoms or N atoms around the Si atom, causing Si atoms to bond together. This is also believed to result in the formation of a defect structure. It is believed that when an H atom enters a location where an O atom or N atom is lacking, the Si atom also bonds with the H atom, forming a Si-H bond. Similarly, it is believed that an N-H bond is formed when an H atom enters a location where an Si atom or O atom is lacking around an N atom.

[0048] In other words, when there are more Si—H bonds than N—H bonds, it can be inferred that a relatively large number of defect structures are formed around the Si atoms, and that a shortage of atoms also results in the formation of a large number of Si—Si bonds. Conversely, when there are more N—H bonds than Si—H bonds, it can be inferred that although defect structures are formed within the molecular structure of compound A1, relatively few defect structures are formed around the Si atoms, and that there are relatively few Si—Si bonds.

[0049] 7 shows examples of infrared absorption spectra of compounds A11 to A13 measured by Fourier transform infrared spectroscopy. Compounds A11 to A13 all fall under the category of compound A1, but differ from one another in composition and structure.

[0050] Wave number 3200-3450nm －１ The peak observed within this range is a peak derived from the stretching vibration of the N-H bond, and this peak is designated as p1 and the peak intensity as v1. －１ The peak observed within this range is a peak derived from the stretching vibration of the Si—H bond, and this peak is designated as p2 and the peak intensity as v2. －１ The peak observed within this range is a peak derived from the deformation vibration of the N-H bond, and this peak is designated as p5, and the peak intensity is designated as v5. －１ The peak observed within this range is a peak derived from the stretching vibration of the Si—O bond, and this peak is designated as p3, and the peak intensity is designated as ν3. －１The peak observed within this range is a peak derived from the stretching vibration of the Si—N bond, and this peak is designated as p4, and the peak intensity is designated as ν4.

[0051] In the present disclosure, the term "peak intensity" refers to a maximum value present within a specific wave number range. －１ When the maximum peak intensity in the range is 1.000, the peak intensity is 0.001 or more. －１ When the maximum peak intensity within the range is taken as 1.000, an intensity of less than 0.001 is not considered to be a peak.

[0052] In the present disclosure, it is not necessary for both peaks p3 and p4 to be confirmed, and only one of the peaks may be confirmed. Peaks p3 and p4 may overlap and be inseparable, and only one of the peaks may be confirmed. Furthermore, it is not necessary for peak p5 to be confirmed. Peaks p3 and p5 may overlap and be inseparable, and only peak p3 may be confirmed.

[0053] For example, in Figure 7, it can be seen that compound A11 has peaks p1, p2, and p3. Furthermore, peaks p4 and p5 cannot be confirmed, but this is thought to be because peaks p3, p4, and p5 overlap and peaks p4 and p5 cannot be separated.

[0054] It can be seen that compound A12 has peaks p1, p2, p3, and p4. Peak p5 cannot be confirmed, but this is thought to be because peaks p3 and p5 overlap and peak p5 cannot be separated.

[0055] It can be seen that compound A13 has peaks p1, p2, p4, and p5. Peak p3 cannot be confirmed, but this is thought to be because peaks p3 and p4 overlap and peak p3 cannot be separated.

[0056] As described above, in the first embodiment, the following formula (a) is satisfied: Formula (a) v1>v2. From this, it can be inferred that Compound A1 has a moderate number of defect structures, but has a moderate number of Si-Si bonds. This makes it possible to reduce the proportion of Si-Si bonds, thereby increasing the transmittance of visible light through the core.

[0057] The peak intensities v1, v2, v3, and v4 may satisfy at least one of the following formulas (b) and (c). Alternatively, they may satisfy both formulas (b) and (c). Formula (b) v1<v3 Formula (c) v1<v4

[0058] Satisfying formula (b) or (c) means that the molecular structure of compound A1 has more Si—O bonds or Si—N bonds than N—H bonds. In other words, the defective structure can be appropriately reduced. This may further improve the transmittance of compound A1.

[0059] The larger of the peak intensities ν3 and ν4 is designated as ν ｍａｘ When the above formula (d) is satisfied, the following formula (d) may be satisfied: ｍａｘ ≧0.001

[0060] Satisfying formula (d) means that the molecular structure of compound A1 has a moderate number of Si—H bonds. In other words, compound A1 may have a moderate number of defect structures. This may further improve the transmittance of compound A1.

[0061] The larger of the peak intensities ν3 and ν4 is designated as ν ｍａｘ When the above formula (e) is satisfied, the following formula (e) may be satisfied: ｍａｘ ≦0.06

[0062] Satisfying formula (e) means that the number of Si—H bonds in the molecular structure of compound A1 is appropriately reduced. In other words, the number of defect structures and Si—Si bonds may be appropriately reduced. This may further improve the transmittance of compound A1.

[0063] The larger of the peak intensities ν3 and ν4 is designated as ν ｍａｘWhen the above formula (f) is satisfied, the following formula (f) may be satisfied: ｍａｘ ≧0.30

[0064] Satisfying formula (f) means that the molecular structure of compound A1 has a moderate number of N—H bonds. In other words, compound A1 may have a moderate number of defect structures. This may further improve the transmittance of compound A1.

[0065] The peak intensities v1 and v2 may satisfy the following formula (g): v2 / v1≦0.20

[0066] Satisfying formula (g) means that the ratio of N—H bonds to Si—H bonds in the molecular structure of compound A1 is within a specific range. In other words, the number of Si—Si bonds may be appropriately reduced while still having a moderate defect structure. This may further improve the transmittance of compound A1.

[0067] The peak intensities v1 and v5 may satisfy the following formula (h): v1>v5

[0068] For example, when compound A1 that satisfies formula (h) is compared with compound A1 that does not satisfy formula (h) while containing the same number of N—H bonds, compound A1 that satisfies formula (h) has H atoms bonded to N atoms more uniformly than compound A1 that does not satisfy formula (h). In other words, compound A1 that satisfies formula (h) can have a more uniform number of N—H bonds per N atom than compound A1 that does not satisfy formula (h), and therefore can improve the strength of a core containing compound A1.

[0069] Furthermore, in the case of an N-H bond, stretching vibration can occur with just one H atom per N atom, but bending vibration requires two or more H atoms per N atom. Stretching vibration is a linear change, whereas bending vibration is a change accompanied by twisting between bonds. In other words, a relatively large peak intensity resulting from bending vibration means that numerous twists have occurred between bonds in compound A1, and the molecular structure of compound A1 is easily distorted. Therefore, compound A1 satisfying formula (h) is less susceptible to distortion in its molecular structure than compound A1 not satisfying formula (h), and the mechanical strength of a core containing compound A1 can be improved.

[0070] [Physical Properties] The apparent density of compound A1 was 2.1 g / cm ３ That is, the number of defective structures may be appropriately reduced in the molecular structure of compound A1, thereby imparting appropriate hardness to compound A1 and reducing deformation.

[0071] The apparent density of compound A1 is 2.4 g / cm ３ The apparent density of the cladding made of silicon dioxide may be 2.25 g / cm or less. In other words, the molecular structure of compound A1 may have a moderate defect structure. This may further improve the transmittance of compound A1. ３ Therefore, warping and cracking of the optical waveguide can be reduced by bringing the apparent density of the core containing compound A1 closer to the apparent density of the cladding made of silicon dioxide. As a result, in an optical waveguide including a cladding made of silicon dioxide and a core containing compound A1, it is possible to provide an optical waveguide that has improved transmission efficiency while reducing warping and cracking of the optical waveguide.

[0072] The apparent density refers to the density when the volume of the solid itself and the internal voids are taken as the volume. In other words, the volume when calculating the apparent density includes the volume of the solid itself and the volume of the internal voids. The apparent density can be measured, for example, by X-ray reflectivity (XRR).

[0073] The Young's modulus of the compound A1 may be 150 GPa or less, preferably 120 GPa or less, and even more preferably 110 GPa or less, which may impart flexibility to the compound A1 and reduce cracking of the core.

[0074] The Young's modulus of compound A1 may be 50 GPa or more, preferably 60 GPa or more, and even more preferably 70 GPa or more. This may impart appropriate hardness to compound A1 and reduce deformation. Here, silicon dioxide is a typical example of a clad material, and the Young's modulus of a clad made of silicon dioxide is 70.1 GPa. As shown in FIG. 9 (described later), in manufacturing an optical waveguide, the core 13 is formed on the lower clad 12B. If warping or deformation occurs in the lower clad 12B or the core 13, and the Young's modulus of the lower clad 12B and the core 13 differ significantly (for example, the difference in Young's modulus is 40 GPa or more), a large difference in the amount of deformation between the lower clad 12B and the core 13 occurs, which may result in warping or cracking of the optical waveguide. Therefore, warping and cracking of the optical waveguide can be reduced by bringing the Young's modulus of the core containing compound A1 closer to the Young's modulus of the cladding made of silicon dioxide, thereby providing an optical waveguide having a cladding made of silicon dioxide and a core containing compound A1, with reduced warping and cracking of the optical waveguide and improved transmission efficiency.

[0075] The Young's modulus can be measured by, for example, nanoindentation. ３ N ４ The Young's modulus of silicon oxide (SiO ) is, for example, 300 GPa. ２ ) is, for example, 76 GPa. In order to improve the Young's modulus of the compound A1, silicon nitride (Si ３ N ４ ) to reduce the Young's modulus, ２ ) to adjust the Young's modulus of the compound A1.

[0076] The hardness of the compound A1 may be 6 GPa or more, and more preferably 8 GPa or more, which may provide the compound A1 with an appropriate hardness and reduce deformation.

[0077] The hardness of compound A1 may be 16 GPa or less, or better, 12 GPa or less. This may impart flexibility to compound A1 and reduce cracking. Since the hardness of the cladding made of silicon dioxide is 7.2 GPa, warping and cracking of the optical waveguide can be reduced by bringing the hardness of the core containing compound A1 closer to the hardness of the cladding made of silicon dioxide. This makes it possible to provide an optical waveguide having a cladding made of silicon dioxide and a core containing compound A1, which has improved transmission efficiency while reducing warping and cracking of the optical waveguide.

[0078] The hardness can be measured by, for example, a nanoindentation method.

[0079] Refractive index n of compound A1 ｃｏｒｅ may be in the range of 1.50 to 2.10, more preferably in the range of 1.55 to 1.80, and even more preferably in the range of 1.65 to 1.75. A refractive index of 1.50 or more can improve the numerical aperture (NA) when an optical waveguide is formed using a cladding made of silicon dioxide. Details of the numerical aperture (NA) will be described later. A refractive index of 2.10 or less can reduce Fresnel reflection occurring at the end face of the optical waveguide. The refractive index can be measured, for example, by spectroscopic ellipsometry.

[0080] The extinction coefficient k of the compound A1 may be 0.002 or less, or more preferably 0.001 or less, thereby further improving the transmittance of the compound A1. The extinction coefficient can be measured, for example, by spectroscopic ellipsometry.

[0081] Second Embodiment In a second embodiment, the core of the optical waveguide contains the following compound A2. When the atomic composition ratio of Si, O, and N in compound A2 measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y, the following formulas (1) and (2) are satisfied: 0<x<2. In the infrared absorption spectrum of Compound A2 measured by Fourier transform infrared spectroscopy, when the peak intensity due to the stretching vibration of the N—H bond is v1 and the peak intensity due to the stretching vibration of the Si—H bond is v2, the following formula (a) is satisfied: formula (a) v1>v2

[0082] Compound A2 contains at least a Si (silicon) atom, an O (oxygen) atom, an N (nitrogen) atom, and an H (hydrogen) atom. Compound A2 may contain other atoms as long as the effects of the present disclosure are achieved.

[0083] The relationship between the peak intensities in the infrared absorption spectrum of Compound A2 is the same as the relationship between the peak intensities in the infrared absorption spectrum of Compound A1. The physical properties of Compound A2 are the same as the physical properties of Compound A1. Therefore, the description of the relationship between the peak intensities in the infrared absorption spectrum and the physical properties will be omitted.

[0084] [Atomic Composition Ratio] In the present disclosure, the term "atomic composition ratio" refers to the ratio of the number of specific atoms when the number of Si (silicon) atoms contained in compound A2 is taken as 1. The atomic composition ratios of Si, O, and N contained in compound A2 can be measured in the same manner as the atomic composition percentages of Si, O, and N contained in compound A1, and fall within the above-mentioned ranges.

[0085] 8 is a graph showing the relationship between x and y when the atomic composition ratio of Si, O, and N is Si:O:N=1:x:y. In the graph of FIG. 8, the horizontal axis represents x (atomic composition ratio of O), and the vertical axis represents y (atomic composition ratio of N).

[0086] The line (1) shown below is a line that represents the relationship between x and y in silicon nitride, silicon oxynitride, or silicon oxide that does not have a defect structure.

[0087] The point on the line (1) at x=0.0 and y=4 / 3 corresponds to silicon nitride (Si) without a defect structure as shown in FIG. ３ N ４) on the line (1). The points within the range of 0<x<2 correspond to silicon oxynitride without a defect structure as shown in FIG. 5. The points on the line (1) where x=2.0, y=0.0 correspond to silicon oxide (SiO ２ ) applies.

[0088] In the graph of Fig. 8, compound A2 is located in the region below the line (1) in the range of 0 < x < 2. In other words, compound A2 has a defective structure due to the generation of dangling bonds in Si atoms.

[0089] The atomic composition ratio of the compound A2 may satisfy the following formula (3).

[0090]

[0091] When compound A2 satisfies formula (3), it is located within the region surrounded by the lines (1), (2), and (3) in the graph of FIG. 8. In this manner, the value of the peak intensity v1 in the infrared absorption spectrum may be adjusted. The molecular structure of compound A2 may be adjusted to have an appropriate number of N-H bonds, that is, to have a defective structure, thereby reducing the number of Si-Si bonds. This may further improve the transmittance of compound A2.

[0092] The atomic composition ratio of the compound A2 may satisfy the following formula (4): Formula (4) y≧−0.39x+0.79 Line (4) y=−0.39x+0.79

[0093] When compound A2 satisfies the above formula (4), it is located within the region surrounded by the above lines (1) and (4) in the graph of Figure 8. In other words, the molecular structure of compound A2 may not have too few defective structures. This may further improve the transmittance of compound A2.

[0094] The atomic composition ratio of the compound A2 may satisfy the following formula (5): y≦0.9 in formula (5) and y=0.9 in line (5).

[0095] When compound A2 satisfies the above formula (5), it is located in the region surrounded by the above lines (1) and (5) in the graph of Figure 8. Specifically, compound A2 is located in the region below line (5) when 0 < x < 0.65, and in the region below line (1) when 0.65 ≤ x < 2. In other words, the molecular structure of compound A2 may have a moderately defective structure. This may impart flexibility to compound A2 and reduce core cracking.

[0096] The above-mentioned atomic composition ratio relationship may also be satisfied in the compound A1.

[0097] The core material of the optical waveguide other than Compound A is silicon oxide (SiO ２ ), silicon nitride (SiN), resins, etc. Examples of resins include acrylic resins, methacrylic resins, polycarbonate, polystyrene, cyclic ether resins (epoxy resins, oxetane resins, etc.), polyamide, polyimide, polybenzoxazole, polysilane, polysilazane, silicone resins, fluorine resins, polyurethane, polyolefin, polybutadiene, polyisoprene, polychloroprene, polyester (polyethylene terephthalate, polybutylene terephthalate, etc.), polyethylene succinate, polysulfone, polyether, and cyclic olefin resins (benzocyclobutene resins, norbornene resins, etc.).

[0098] <Optical Waveguide> In the present disclosure, "optical waveguide" refers to a transmission path for transmitting light rays. Examples of light rays include visible light and electromagnetic waves other than visible light (e.g., infrared light). The light rays may have any wavelength that can be transmitted by the optical waveguide of the present disclosure. In the present disclosure, "visible light" refers to light with a wavelength in the range of 380 to 780 nm.

[0099] FIG. 1 is a perspective view of an optical waveguide 1 according to this embodiment. The optical waveguide 1 includes a clad 2 and a core 3. The clad 2 may surround the core 3. In FIG. 1, the clad 2 is positioned to entirely surround the core 3, but the present disclosure is not limited thereto. For example, the clad 2 may be positioned to partially surround the core 3. A light ray 4 enters in the direction of the arrow shown in FIG. 1 and is transmitted through the optical waveguide 1. The optical waveguide 1 may further include a protective coating on the outer periphery of the clad 2.

[0100] Fig. 9 is a cross-sectional view of an example of an optical waveguide 11 according to this embodiment. The optical waveguide 11 includes an upper clad 12A, a lower clad 12B, and a core 13. As shown in Fig. 9, a plurality of cores 13 may be collectively sandwiched between the upper clad 12A and the lower clad 12B. The optical waveguide 11 does not necessarily have to include the upper clad 12A. The materials constituting the upper clad 12A and the lower clad 12B may be the same or different.

[0101] The clad material of the optical waveguide is not particularly limited, and silicon oxide (SiO ２ The cladding may be made of silicon nitride (SiN), silicon nitride (SiN), resin, etc., and in particular may be made of silicon oxide as the main component. Note that the "main component" in the cladding refers to a component whose content relative to the total mass of the cladding is 50 mass % or more. This may result in an optical waveguide with improved optical transmission efficiency. The resin may also be any of the resins listed as the core material.

[0102] Silicon oxynitride may also be used as the cladding material of the optical waveguide. In this case, the refractive index of the cladding material is different from the refractive index of the core material. With this configuration, the refractive indices of the cladding and core can be freely adjusted, and the refractive index difference between the cladding and core can be reduced compared to when the cladding material is primarily made of silicon oxide. This allows the optical transmission mode in the optical waveguide to approach single mode from multimode. In particular, in Experimental Examples 16 and 17 described below, the optical transmission mode in the optical waveguide is closer to single mode than multimode. In such a case, by using silicon oxynitride as the cladding material as well, the refractive index of the cladding and core can be relatively freely adjusted, and the refractive index difference between the cladding and core can be reduced compared to when the cladding material is primarily made of silicon oxide.

[0103] The optical waveguide of this embodiment may be single-mode or multi-mode. "Mode" refers to the optical transmission path. In multi-mode, there are multiple optical transmission paths, and many types of light can be transmitted. This also makes the multi-mode optical waveguide resistant to bending and less susceptible to light leakage.

[0104] In the case of a multimode waveguide, one method for improving the optical transmission efficiency is to increase the numerical aperture (NA). The larger the "numerical aperture (NA)", the larger the maximum incident / exit angle at which light that can be transmitted through the optical waveguide can be incident.

[0105] 10 is an explanatory diagram of the numerical aperture of the optical waveguide 1. Light emitted from an LD (laser diode) light source 15 enters the optical waveguide 1 from the end face of the optical waveguide 1. The incident light 16 incident from the end face of the optical waveguide 1 is transmitted while repeatedly undergoing total reflection at the boundary between the clad 2 and the core 3. The incident angle of the incident light 16 when the incident light 16 is totally reflected at the boundary between the clad 2 and the core 3 and the reflected light travels along the boundary surface between the clad 2 and the core 3 is defined as θ [°]. Let n be the refractive index of the medium around the optical waveguide 1, and n be the refractive index of the clad 2. ｃｌａｄ , the refractive index of the core 3 is n ｃｏｒｅIn this case, the numerical aperture is defined by the following formula: However, when the medium surrounding the optical waveguide 1 is air, n=1.

[0106]

[0107] From the above formula, it can be seen that the numerical aperture increases as the difference in refractive index between the cladding 2 and the core 3 increases. The difference in refractive index depends on the structure of the core 3, such as its shape, but may be within the range of 0.01 to 0.25, for example.

[0108] Fig. 11 is a graph showing the relationship between the numerical aperture and the light-receiving angle range 2θ [°]. As shown in Fig. 10, when the incident angle defined above is θ [°], the light-receiving angle range is expressed in 2θ [°]. As shown in Fig. 11, it can be seen that the larger the value of the numerical aperture, the larger the value of the light-receiving angle range 2θ [°].

[0109] Furthermore, by reducing the difference in Young's modulus between the core and the cladding, warping and cracking of the optical waveguide can be reduced.

[0110] In this embodiment, the cladding contains silicon oxide as a main component, so that the numerical aperture can be made relatively high and the difference in Young's modulus between the core and the cladding can be made relatively small.

[0111] In addition, the film quality of the core and clad may be made uniform to reduce scattering of light and improve the transmission efficiency of the optical waveguide.

[0112] When the core has a thickness of 4 μm, a width of 5 μm, and a length of 2.5 mm, the optical waveguide may have a transmission efficiency of 55% or more for light with a wavelength of 450 nm. The transmission efficiency of 450 nm light may be even better, 60% or more. This may further improve the optical transmission efficiency of the optical waveguide.

[0113] An example of the shape of an optical waveguide is shown in Figure 1. The shape of the optical waveguide 1 is not particularly limited, and may be fiber-like or long. Even with such a shape, the transmittance of the core 3 is excellent, so the transmission loss of the optical waveguide 1 can be reduced. The width and thickness of the optical waveguide 1 may be in the range of 1 to 100 µm, or more preferably in the range of 3 to 15 µm. The length L of the optical waveguide 1 may be in the range of 0.1 to 10 mm, or more preferably in the range of 0.2 to 3 mm.

[0114] The cross-sectional shape of the core 3 is not particularly limited, and may be rectangular as shown in Fig. 1, trapezoidal, or circular. When the core 3 is rectangular, the width W and thickness D of the core 3 may be in the range of 0.1 to 6 µm, or more preferably in the range of 0.5 to 5 µm. When the core 2 is circular, the diameter of the core 2 may be in the range of 0.1 to 6 µm, or more preferably in the range of 0.5 to 5 µm.

[0115] <<Method for Manufacturing Optical Waveguide>> An example of a method for manufacturing an optical waveguide according to this embodiment will be described below, but the present disclosure is not limited thereto. In the manufacturing method described below, the core and cladding are formed by chemical vapor deposition (CVD). In the CVD method, raw material gases (gases) for the core and cladding are supplied, and energy such as heat, plasma, or light is applied, resulting in a chemical reaction that causes a film to be adsorbed and deposited on the surface of a substrate.

[0116] The source gas for compound A contained in the core is not particularly limited, and may be monosilane gas (SiH ４ ), ammonia gas (NH ３ ), nitrous oxide gas (N ２ O), nitrogen gas (N ２ ) etc. may also be used.

[0117] The film formation conditions for forming the core are as follows: The film formation temperature is not particularly limited and may be in the range of 220 to 380°C. The film formation pressure is not particularly limited and may be in the range of 60 to 90 Pa. The RF output of the plasma treatment is not particularly limited and may be in the range of 30 to 70 W. Here, "RF output" refers to the energy of a high-frequency power source for turning the raw material gas into plasma and causing a chemical reaction.

[0118] The atomic composition and molecular structure of compound A contained in the core can be adjusted by the ratio of raw material gases and film formation conditions.

[0119] The method for producing the clad is not particularly limited, and a conventionally known method can be applied. The source gas for the clad is not particularly limited, and monosilane gas (SiH ４ ), oxygen gas (O ２ In forming the cladding, the film formation conditions are not particularly limited.

[0120] 9, the optical waveguide 1 may be formed by first forming the lower clad 12B and then forming the core 13. After that, the upper clad 12A may be formed so as to surround the periphery of the core 13. The upper clad 12A and the lower clad 12B may be formed of the same material, or may be formed of different materials. Furthermore, the upper clad 12A and the lower clad 12B may be formed by the same method, or may be formed by different methods.

[0121] The core 13 can be formed by forming a layer containing a core material on the lower clad 12B, then forming a mask layer, dry etching, and removing the mask layer.

[0122] <Light-Emitting Module> The optical waveguide 1 of the present embodiment may be included in a light-emitting module 100. The light-emitting module 100 may be mounted on an electronic module, an electronic device, or the like. The electronic device may be, for example, an augmented reality (AR) glass, which is a type of smart glass, a head-up display, a projector, or the like. Furthermore, the light-emitting module 100 may be used in, for example, a lighting device such as a headlight or a turn signal of a vehicle, such as a car.

[0123] 2 is an overall perspective view of a light-emitting module 100 having the optical waveguide 1 of this embodiment. The light-emitting module 100 includes an optical waveguide module 10, a lens 20, a light-emitting element 30, a lid 40, etc. The optical waveguide module 10 includes a substrate 11, a clad 12, a core 13, an electrode 14, etc.

[0124] 2, a plane parallel to the plane including the waveguide path (the central axis of the core 13) is defined as the XY plane, and the X axis (first direction) is defined along the longitudinal direction. The Y axis (second direction) is a direction perpendicular to the X axis within the XY plane. The Z axis is defined as the upward direction perpendicular to the XY plane. In a plan view seen from above along the Z axis, the optical waveguide module 10 of this embodiment has a substantially rectangular shape, but is not limited to this.

[0125] In this embodiment, the substrate 11 may be a silicon substrate or an insulating material such as a ceramic material. Examples of the ceramic material include an aluminum oxide sintered body, a mullite sintered body, a silicon carbide sintered body, an aluminum nitride sintered body, a silicon nitride sintered body, and a glass ceramic sintered body. The material of the substrate 11 may be an organic material. Examples of the organic material include an epoxy resin, a polyimide, a polyester, an acrylic resin, a phenolic resin, and a fluororesin.

[0126] The core 13 is located inside the cladding 12 and transmits light. Light incident on one end of the core 13 is transmitted along the core 13. The light-emitting module 100 has three independent cores 13. The cross-sectional shape of each core 13 perpendicular to the central axis (extension direction) may be rectangular or trapezoidal.

[0127] The cladding 12 is located on one surface of the flat substrate 11, in this case the +Z side surface. The cores 13 in the cladding 12 are exposed from the cladding 12 on two different surfaces in the longitudinal direction (X direction) of the optical waveguide module 10. The three cores 13 are arranged spaced apart from each other in the Y direction. The end surface on the +X side of the cladding 12 is the output surface S1.

[0128] The cladding 12 may have protrusions 121 that protrude upward along the cores 13 within a range that includes the cores 13 in a plan view (planar perspective). The cladding 12 may also have protrusions 122 in the −X direction between the end faces of the cores 13, i.e., on both sides of the central core 13.

[0129] The cladding 12 may have a recess C1 that is open in the −X direction of the core 13 on the side (+Z direction) opposite to the surface facing the upper surface of the substrate 11. The cladding 12 may have an optical waveguide portion 12L in the +X direction of the recess C1 in which the core 13 is located, and wall portions 12W that are sidewall portions connected to the optical waveguide portion 12L and surround the recess C1 on three sides, i.e., in the ±Y directions and the −X direction.

[0130] The light-emitting element 30 is located on the electrode pad of the first electrode 141 and is electrically connected to the electrode pad. The second electrode 142 is electrically connected to the other electrode of the light-emitting element 30. Each electrode 14 may extend to the outside of the recess C1 through between the wall portion 12W of the cladding 12 and the substrate 11. When a drive voltage is applied between each pair of the first electrode 141 and the second electrode 142 outside the recess C1, the light-emitting element 30 emits light.

[0131] The light-emitting element 30 may be, for example, a laser diode (LD) that emits light at a predetermined wavelength. The light-emitting module 100 may have three light-emitting elements 30 corresponding to the three cores 13, respectively. The three light-emitting elements 30 may be, for example, a red-emitting LD, a green-emitting LD, and a blue-emitting LD. The light-emitting element 30 may be a light-emitting diode (LED).

[0132] A lens 20 may be located on the output side of the end face of the optical waveguide module 10. The lens 20 may be, for example, a convex lens, a diffractive lens, a rod lens, or a ball lens. A lid 40 may be bonded to the cladding 12 around the upper periphery of the recess C1. In other words, the lid 40 may cover the element mounting region M and seal the recess C1.

[0133] In addition, the specific configurations, structures, positional relationships, materials, etc. shown in the above embodiments can be appropriately changed without departing from the spirit of the present disclosure. The scope of the present invention includes the scope of the invention described in the claims and its equivalents.

[0134] The present disclosure will be specifically described below with reference to examples, but the present disclosure is not limited thereto. In the following examples, unless otherwise specified, operations were performed at room temperature (25°C).

[0135] <<Fabrication of Optical Waveguides>> Optical waveguides 1 to 17 were fabricated by the above-described method for fabricating an optical waveguide. The atomic composition and molecular structure of compound A contained in the core were adjusted by changing the ratio of raw material gases and film formation conditions.

[0136] Tables I and II show the atomic composition of the core of each of the optical waveguides 1 to 17 and the peak intensities in the infrared absorption spectrum. The peak intensities v1 to v5 shown in Tables I and II are the larger peak intensities v3 and v4. ｍａｘ In the optical waveguides 1 to 17, the core material is Compound A, and the clad material is silicon oxide (SiO ２ )

[0137]

[0138]

[0139] Measurement by X-ray photoelectron spectroscopy (XPS) was carried out by the following method and conditions. The sample of Compound A was prepared by depositing a film corresponding to the core of the optical waveguide on a Si substrate with a thickness of 0.5 to 0.6 mm, a width of 5 to 15 mm, and a length of 5 to 15 mm. The thickness of the film corresponding to the core was set to a range of 2 to 5 μm.

[0140] The measurement device used was an X-ray photoelectron spectrometer "PHI Quantera II" (manufactured by ULVAC-PHI Corporation). AlKα rays were used as the X-ray source, and the X-ray irradiation conditions were a beam diameter of 100 μm and an acceleration voltage of 15 kV. The measurement area was a range of approximately 100 μm in diameter. The detector conditions were a pass energy of 224 eV and a step size of 0.4 eV. Ar sputtering was performed at an acceleration voltage of 4 kV. The etching rate using silicon oxide was applied to convert the depth (6.72 nm / min).

[0141] The atomic composition ratio and atomic composition ratio were calculated based on the binding energy value for the atomic nucleus of each atom obtained from the photoelectron spectrum measured by X-ray photoelectron spectroscopy. The atomic composition ratio was Si:O:N=1:x:y.

[0142] 12 is a graph plotting the relationship between x and y when the atomic composition ratio of Si, O, and N is Si:O:N=1:x:y, and Experimental Examples 1 to 15. As shown in FIG. 12, it can be seen that the plots for Examples 1 to 15 are within the specific region described above.

[0143] Infrared absorption spectra were measured by Fourier transform infrared spectroscopy under the following conditions. The sample of Compound A was prepared by depositing a film corresponding to the core of the optical waveguide on a Si substrate with a thickness of 0.5 to 0.6 mm, a width of 5 to 15 mm, and a length of 5 to 15 mm. The thickness of the film corresponding to the core was set to a range of 2 to 5 μm.

[0144] The measurement device used was a Fourier transform infrared (FT-IR) spectrophotometer "Nicolet iN10 MX" (manufactured by Thermofisher Scientific). The measurement parameters of the Fourier transform infrared (FT-IR) spectrophotometer were as follows: Resolution: 8.00 cm －１ Number of accumulations: 64 Measurement mode: Pinpoint measurement Measurement method: Microscopic ATR method Detector: MCT detector Wave number range: 4000 to 675 cm －１ Background: Air

[0145] 13 to 19 are infrared absorption spectrum diagrams measured by Fourier transform infrared spectroscopy for Experimental Examples 1 to 17. In Figs. 13 to 19, the vertical axis represents intensity, and the horizontal axis represents wave number [cm －１ Regarding the intensity, the larger of the peak intensities v3 and v4 is ｍａｘ The value is expressed as a ratio when the value is set to 1.000.

[0146] Tables III and IV show the relationship between each core of optical waveguides 1 to 17 and the above formulas (a) to (h) and (1) to (5). In the tables, "applicable" indicates that the relationship of the corresponding formula is satisfied, and "not applicable" indicates that the relationship of the formula is not satisfied. "-" indicates that an evaluation of whether the relationship of the formula is satisfied was not performed.

[0147]

[0148]

[0149] <Evaluation of Physical Properties of Core> The cores of the obtained optical waveguides 1 to 17 were evaluated as follows.

[0150] (Young's modulus and hardness) Young's modulus and hardness were measured using the following method and conditions. Samples were prepared by depositing a film corresponding to the core of the optical waveguide on a Si substrate with a thickness of 0.5 to 0.6 mm, a width of 5 to 100 mm, and a length of 5 to 100 mm. The thickness of the film corresponding to the core was set to a range of 2 to 5 μm. Measurements were performed using the standard procedure of the nanoindentation method defined in "ISO 14577-1:2015 Metallic materials - Instrumented indentation test for hardness and materials parameters -".

[0151] The measuring device used was a nanoindenter "TI980" (manufactured by Bruker). The transducer was STD-3D, and the indenter pressing load was 6000 μN. The measurement temperature was room temperature (25°C). The samples were mirror-finished to ensure that the cross-sectional area of ​​the core was 10 times the area of ​​the indenter. Measurements were performed on 10 cross-sectional samples, and the arithmetic mean values ​​of the Young's modulus and hardness determined for each sample were used as the Young's modulus and hardness of the core. Data that appeared to be abnormal at first glance were excluded.

[0152] (Apparent Density) The apparent density was measured using the following method and conditions. The sample used was a film corresponding to the core of the optical waveguide, formed on a Si substrate with a thickness of 0.5 to 0.6 mm, a width of 5 to 30 mm, and a length of 5 to 30 mm. The thickness of the film corresponding to the core was set to a range of 0.05 to 0.2 μm. The measurement was performed using X-ray reflectivity (XRR) on a fully automated multipurpose X-ray diffractometer "SmartLab" (manufactured by Rigaku Corporation). The measurement parameters were as follows: Measurement method: X-ray reflectivity measurement (XRR) X-ray generator: Cu anticathode, output 45 kV 200 mA Incident optical system: Ge (111) asymmetric beam compression crystal Soller slit: 5.0° on the receiving side Slit: Incident side IS = 0.05 mm, receiving side RS1 = 0.1 mm, RS2 = 0.1 mm Scanning conditions: Scan axis 2θ / ω, scan speed 0.2° / min, step width 0.002°, analysis range 0.3 to 3.0°

[0153] (Refractive index and extinction coefficient) Refractive index n ｃｏｒｅThe extinction coefficient k was measured using the following method and conditions. The samples used were films corresponding to the core of the optical waveguide, deposited on a Si substrate with a thickness of 0.5 to 0.6 mm, a width of 5 to 100 mm, and a length of 5 to 100 mm. The thickness of the film corresponding to the core was within the range of 0.05 to 0.2 μm. The measurement device used was a spectroscopic ellipsometer "UVISEL2" (manufactured by Horiba, Ltd.). The incident angle was within the range of 50 to 80°, the measurement range was 0.6 to 6.5 eV (190.76 to 2066.54 nm), the measurement interval was 0.05 eV, and the measurement spot diameter was 2030 μm x 705 μm at 70° incidence. Comparison of each level was performed at 632.8 nm.

[0154] Tables V and VI show the physical properties (Young's modulus, hardness, apparent density, refractive index, and extinction coefficient) of the cores of the optical waveguides 1 to 17. Note that "-" in the tables indicates that no measurement was performed.

[0155]

[0156]

[0157] <Evaluation of Optical Waveguides> The following evaluations were performed on the obtained optical waveguides 1 to 15. For the optical waveguide samples, a lower clad of 2 μm in thickness, a core of 4 μm in thickness, and an upper clad of 2 μm in thickness were laminated on a Si substrate with a thickness of 0.5 to 0.6 mm, a width of 2 to 3 mm, and a length of 2.5 mm. The width of the core cross section was set to 5 μm. In the optical waveguides 16 and 17, the core has a thickness and width of 2 μm or 3 μm, and a length of 2.5 mm.

[0158] Only the cladding of the optical waveguide was prepared, and the following items were measured for the cladding using the same method and procedure as for the core: Atomic composition ratio Si: 34.0%, O: 65.0% Young's modulus 70.1 [GPa] Hardness 7.2 [GPa] Apparent density 2.25 [g / cm ３ ] Refractive index 1.497 (measured at a wavelength of 632.8 nm)

[0159] (Transmission Efficiency) The transmission efficiency (transmittance) was calculated by emitting light from a semiconductor laser element having a wavelength of 450 nm, placed 5 μm away from the input end of the optical waveguide, and dividing the amount of light that passed through the optical waveguide and emerged from the output end by the amount of light from the semiconductor laser element. In Table VIII, for optical waveguides 16 and 17, the transmission efficiencies when the core thickness and width were both 2 μm are shown, and the figures in parentheses show the transmission efficiencies when the core thickness and width were both 3 μm.

[0160] The obtained transmission efficiency was evaluated according to the following criteria. Note that a grade of B or higher (A to B) was deemed acceptable for practical use and was considered to be acceptable. A: Transmission efficiency of 65% or higher. B: Transmission efficiency of 50% or higher but less than 65%. C: Transmission efficiency of less than 50%. Note that for optical waveguides 16 and 17, the optical transmission mode is closer to single mode than multimode, so the transmission efficiency is generally lower than for optical waveguides 1 to 15, whose optical transmission mode is multimode. For this reason, only the numerical values ​​of the transmission efficiency are shown for optical waveguides 16 and 17, and evaluation was not performed using the same criteria as for optical waveguides 1 to 15.

[0161] (Numerical aperture) The same procedure as for the core is used to determine the refractive index n ｃｌａｄ was measured, and the numerical aperture (NA) was calculated from the above formula.

[0162] The obtained numerical aperture (NA) was evaluated according to the following criteria. Note that a rating of B or higher (A to B) was deemed acceptable for practical use. A: The numerical aperture (NA) was 0.50 or higher. B: The numerical aperture (NA) was 0.25 or higher but less than 0.50. C: The numerical aperture (NA) was less than 0.25. Note that for optical waveguides 16 and 17, the optical transmission mode is closer to single mode than multimode, so the numerical aperture is generally lower than for optical waveguides 1 to 15, whose optical transmission mode is multimode. For this reason, only the numerical aperture values ​​are shown for optical waveguides 16 and 17, and evaluation was not performed using the same criteria as for optical waveguides 1 to 15.

[0163] (Cracks) After the core was formed on the lower cladding, the condition of the optical waveguide sample was visually observed and evaluated according to the following criteria. Grades B and above (A to B) were deemed acceptable for practical use and passed. The evaluation of cracks was based on the case where the cladding material was silicon oxide, and "impossible to use" here means that the sample is impractical when made of silicon oxide. Therefore, if a different material is used for the cladding, it does not necessarily mean that the sample is impractical. A: No cracks were observed in the sample. B: Some cracks were observed in the sample, but the sample was still usable. C: Large cracks were observed in the sample, making it impractical.

[0164] The evaluation results are shown in Tables VII and VIII, where "-" indicates that no measurement was performed.

[0165]

[0166]

[0167] Experimental Examples 1 to 15 show that the optical waveguide of the present disclosure has excellent transmission efficiency, that is, excellent transmission efficiency.

[0168] Furthermore, the optical waveguides in Experimental Examples 16 and 17 have an optical transmission mode that is more similar to single mode than multimode compared to Experimental Examples 1 to 15. Generally, as the optical transmission mode approaches single mode, the transmission efficiency generally decreases. However, as shown in Table VIII, the optical waveguides in Experimental Examples 16 and 17 have an excellent optical transmission efficiency of 35% or more, even when the optical transmission mode is more similar to single mode than multimode, demonstrating excellent transmission efficiency.

[0169] The present disclosure can be used in optical waveguide cores, optical waveguides, light-emitting modules, and electronic devices.

[0170] REFERENCE SIGNS LIST 1 Optical waveguide 2 Cladding 3 Core 4 Light ray 5 Defect structure W Core width D Core thickness L Core length 5 Defect structure 10 Optical waveguide module 11 Substrate 12 Cladding 12A Upper cladding 12B Lower cladding 12L Optical waveguide portion 12W Wall portion 121, 122 Protrusion 13 Core 14 Electrode 141 First electrode 142 Second electrode 15 LD light source 16 Incident light 20 Lens 30 Light emitting element 40 Lid C1 Recess M Element mounting area S1 Emission surface 100 Light emitting module

Claims

1. A core for an optical waveguide containing a compound whose atomic composition percentages of Si, O, and N measured by X-ray photoelectron spectroscopy are: Si: in the range of 34.0 to 60.0 at %, O: in the range of 1.0 to 65.0 at %, N: in the range of 1.0 to 50.0 at %, and wherein in an infrared absorption spectrum measured by Fourier transform infrared spectroscopy, the peak intensity due to the stretching vibration of the N-H bond is v1 and the peak intensity due to the stretching vibration of the Si-H bond is v2, the compound satisfies the following formula (a): v1>v2.

2. When the atomic composition ratio of Si, O, and N measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y, the following formulas (1) and (2) are satisfied, and formula (1) 0<x<2 A core of an optical waveguide containing a compound that satisfies the following formula (a): v1>v2, where v1 is the peak intensity due to the stretching vibration of an N-H bond and v2 is the peak intensity due to the stretching vibration of an Si-H bond in an infrared absorption spectrum measured by Fourier transform infrared spectroscopy.

3. The optical waveguide core according to claim 1 or 2, wherein, in an infrared absorption spectrum of the compound measured by Fourier transform infrared spectroscopy, the peak intensity resulting from the stretching vibration of the Si-O bond is v3 and the peak intensity resulting from the stretching vibration of the Si-N bond is v4, at least one of the following formulas (b) or (c) is satisfied: Formula (b) v1<v3 Formula (c) v1<v4 4. In the infrared absorption spectrum of the compound measured by Fourier transform infrared spectroscopy, the larger of the peak intensity v3 due to the stretching vibration of the Si—O bond and the peak intensity v4 due to the stretching vibration of the Si—N bond is defined as v ｍａｘ When the above equation is satisfied, the following equation (d) is satisfied: ｍａｘ ≧0.001 . The core of an optical waveguide according to claim 2 .

5. In the infrared absorption spectrum of the compound measured by Fourier transform infrared spectroscopy, the larger of the peak intensity v3 due to the stretching vibration of the Si—O bond and the peak intensity v4 due to the stretching vibration of the Si—N bond is defined as v ｍａｘ When the above equation is satisfied, the following equation (e) is satisfied: ｍａｘ ≦0.060 The core of the optical waveguide according to claim 4.

6. In the infrared absorption spectrum of the compound measured by Fourier transform infrared spectroscopy, the larger of the peak intensity v3 due to the stretching vibration of the Si—O bond and the peak intensity v4 due to the stretching vibration of the Si—N bond is defined as v ｍａｘ When the above equation is satisfied, the following equation (f) is satisfied: ｍａｘ ≧0.300 . The core of an optical waveguide according to any one of claims 1 to 5.

7. The core of an optical waveguide according to any one of claims 1 to 6, wherein the compound satisfies the following formula (g) in an infrared absorption spectrum measured by Fourier transform infrared spectroscopy: formula (g) v2 / v1≦0.

20.

8. The optical waveguide core according to any one of claims 1 to 7, wherein the compound satisfies the following formula (h): v1>v5, where v5 is the peak intensity resulting from the deformation vibration of the N-H bond in the infrared absorption spectrum measured by Fourier transform infrared spectroscopy.

9. An optical waveguide core according to any one of claims 1 to 8, wherein the refractive index of the compound is in the range of 1.5 to 2.1, and the Young's modulus of the compound is in the range of 50 to 150 GPa.

10. When the atomic composition ratio of Si, O, and N of the compound measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y, the compound satisfies the following formula (3): An optical waveguide core according to any one of claims 1 to 9.

11. The optical waveguide core according to any one of claims 1 to 10, wherein the compound satisfies the following formula (4) when the atomic composition ratio of Si, O, and N measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y: Formula (4) y≧-0.39x+0.

79.

12. The core of an optical waveguide according to any one of claims 1 to 11, wherein the compound satisfies the following formula (5) when the atomic composition ratio of Si, O, and N measured by X-ray photoelectron spectroscopy is Si:O:N=1:x:y: Formula (5) y≦0.

9.

13. The apparent density of the compound is 2.1 g / cm ３ The core of an optical waveguide according to any one of claims 1 to 12, wherein:

14. A core for an optical waveguide according to any one of claims 1 to 13, wherein the Young's modulus of the compound is 120 GPa or less.

15. A core for an optical waveguide according to any one of claims 1 to 14, wherein the compound has a Young's modulus of 60 GPa or more.

16. An optical waveguide core according to any one of claims 1 to 15, wherein the refractive index of the compound is in the range of 1.55 to 1.

80.

17. An optical waveguide comprising: a core according to any one of claims 1 to 16; and a clad surrounding the core, wherein the clad is made of SiO ２ An optical waveguide comprising as a main component:

18. The optical waveguide according to claim 17, wherein the transmittance of light with a wavelength of 450 nm is 55% or more when the core has a thickness of 4 μm, a width of 5 μm, and a length of 2.5 mm.

19. A light-emitting module comprising an optical waveguide module and a light-emitting element, wherein the optical waveguide module comprises the optical waveguide according to claim 17 or 18, a substrate, and an electrode.

20. An electronic device equipped with the light-emitting module according to claim 19.

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