Optical waveguide and optical member having optical waveguide

Abstract

Provided is an optical waveguide comprising a core part that propagates light and a clad part having a lower refractive index than the core part, wherein the clad part has an underclad part located on one surface of the core part, wherein when the direction of a line where the core part and the underclad part are in contact with each other is defined as the width direction, and a direction perpendicular to the width direction is defined as the thickness direction in a cross-sectional shape of the core part in a direction perpendicular to the light propagation direction, (i) H / L is 0.4 to 3 where L [μm] represents the maximum length of a cross section of the core part in the width direction and H [μm ] represents the maximum length of the cross section in the thickness direction, or (ii) a taper angle of the core part, which is defined as an angle formed by the underclad and the tangent of a core side part corresponding to half the length of the maximum length of the core part in the thickness direction, is between 50° and 130°, inclusive, and wherein at least one of the core part and the clad part is composed of a cured material obtained by curing an organopolysiloxane-containing composition with a specific structure.

Description

Optical waveguide and optical member having optical waveguide

[0001] The present invention relates to an optical waveguide and an optical member having an optical waveguide.

[0002] In fields such as communications, as communication speeds increase, the transmission of optical signals using optical waveguides has attracted attention (Patent Document 1). In particular, optical waveguides made of polymers are being developed in various ways because they can be fabricated using low-temperature processing processes such as photolithography and are easy to mount on a substrate. For example, Patent Document 1 discloses a polymer optical waveguide in which the height and width of a core portion constituting the waveguide are within a specific range, and attempts have been made to provide a polymer optical waveguide with reduced transmission loss of optical signals.

[0003] International Publication No. 2018 / 168783

[0004] However, the above-mentioned prior art technologies have not been able to sufficiently reduce the transmission loss of optical signals, and further reduction in transmission loss is desired. Depending on the configuration of the optical waveguide, there is a risk that polarization-dependent loss in optical transmission may increase, and the transmission loss changes depending on the polarization state of the incident light, so improvements have been required.

[0005] An object of the present invention is to provide an optical waveguide having reduced transmission loss and low polarization dependent loss.

[0006] As a result of extensive research, the present inventors have found that an optical waveguide having a core portion and an undercladding portion that is in contact with a part of the core portion and has a smaller refractive index than the core portion, and the core portion has a specific cross-sectional shape, can reduce transmission loss and polarization dependent loss, and have arrived at the present invention.

[0007] (1) An optical waveguide comprising a core portion that propagates light and a cladding portion having a refractive index lower than that of the core portion, wherein the cladding portion has an undercladding portion that contacts a part of the core portion, wherein in a cross-sectional shape of the core portion in a direction perpendicular to the light propagation direction, the direction of the line where the core portion and the undercladding portion contact each other is the width direction, and the direction perpendicular to the width direction is the thickness direction, and where the maximum length in the width direction of the cross section of the core portion is L [μm] and the maximum length in the thickness direction is H [μm], H / L is 0.4 to 3, and at least one of the core portion and the cladding portion is made of a cured product obtained by curing an organopolysiloxane-containing composition having a polymerizable functional group, represented by the following formula [1]. (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (SiO ４／２ ) Ｑ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[1] [In formula [1], R １ ~R ５ , R ７ ~R １１ R are each independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of organic groups are present, they may be the same or different from one another, and 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0≦Q, 0<M2+D2+T2, 0<D1+D2+T1+T2+Q, M1+M2+D1+D2+T1+T2+Q=1. (2) An optical waveguide comprising a core portion that propagates light and a cladding portion having a refractive index lower than that of the core portion, wherein the cladding portion has an undercladding portion in contact with a part of the core portion, wherein in a cross-sectional shape of the core portion in a direction perpendicular to the light propagation direction, the direction of the line where the core portion and the undercladding portion meet is the width direction, and the direction perpendicular to the width direction is the thickness direction, and when the angle formed by the undercladding and a tangent to a core side portion corresponding to half the maximum length of the core portion in the thickness direction is defined as the taper angle of the core portion, the taper angle is 50° or more and 130° or less, and at least one of the core portion and the cladding portion is made of a cured product obtained by curing an organopolysiloxane-containing composition having a polymerizable functional group, which is represented by the following formula [1]. (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (SiO ４／２ ) Ｑ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[1] [In formula [1], R １~R ５ , R ７ ~R １１ R are each independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of organic groups are present, they may be the same or different, and 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0≦Q, 0<M2+D2+T2, 0<D1+D2+T1+T2+Q, M1+M2+D1+D2+T1+T2+Q=1.

[0008] (3) The optical waveguide according to (1) or (2) above, wherein the difference in refractive index between the core and the cladding is 0.005 or more and 0.05 or less. (4) The optical waveguide according to any of (1) to (3) above, wherein, in a cross-sectional shape of the core in a direction perpendicular to the light propagation direction, the length in the thickness direction of the undercladding is 1 μm or more. (5) The optical waveguide according to any of (1) to (4) above, wherein the cladding has an overcladding present in a portion of the core not in contact with the undercladding. (6) The optical waveguide according to any of (1) to (5) above, wherein the refractive index of the core at a wavelength of 1300 nm is 1.400 or more and 1.520 or less.

[0009] (7) The optical waveguide according to any one of (1) to (6) above, wherein the organopolysiloxane having a polymerizable functional group is represented by the following formula [2]: (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (SiO ４／２ ) Ｑ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[2] [In formula [2], R １ ~R ５ , R ７ ~R １１ R are each independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of groups are present, they may be the same or different, and 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0<Q, 0<M2+D2+T2, where M1+M2+D1+D2+T1+T2+Q=1.] (8) The optical waveguide according to any one of the above (1) to (6), wherein the organopolysiloxane having a polymerizable functional group is represented by the following formula [3]. (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２) Ｔ２ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[3] [In formula [3], R １ ~R ５ , R ７ ~R １１ R are each independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of organic groups are present, they may be the same or different, and 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0<D1+D2+T1+T2, 0<M2+D2+T2, and M1+M2+D1+D2+T1+T2=1.

[0010] (9) The optical waveguide according to any one of (1) to (6) above, wherein in formula [1], 0.02≦Y1≦0.25. (10) The optical waveguide according to any one of (1) to (6) above, wherein in formula [1], 0<M2+D2+T2≦0.25. (11) The optical waveguide according to any one of (1) to (6) above, wherein in formula [1], 0.12<M2+D2+T2≦0.25. (12) The optical waveguide according to (7) above, wherein in formula [2], 0.02≦Y1≦0.25. (13) The optical waveguide according to (7) or (12) above, wherein in formula [2], 0.04≦Q. (14) The optical waveguide according to (8) above, wherein in formula [3], 0<D1+D2. (15) The optical waveguide according to (8) or (14) above, wherein in the formula [3], 0.1<D1+D2. (16) The optical waveguide according to (8), (14) or (15) above, wherein in the formula [3], 0<D1. (17) The optical waveguide according to any one of (8), (14) to (16) above, wherein in the formula [3], 0.02≦Y1≦0.25. (18) The optical waveguide according to any one of (8), (14) to (17) above, wherein in the formula [3], 0<T1+T2. (19) The optical waveguide according to any one of (8), (14) to (18) above, wherein in the formula [3], 0<D1+D2 and 0<T1+T2. (20) The R ６ (21) The optical waveguide according to any one of (1) to (19) above, wherein R contains a polymerizable alkenyl group. ６ (22) The optical waveguide according to any one of (1) to (21) above, wherein the organopolysiloxane having a polymerizable functional group does not contain an aromatic structure. (23) The optical waveguide according to any one of (1) to (21) above, wherein the R ６ is an acryloyloxypropyl group and / or a methacryloyloxypropyl group. (24) The optical waveguide according to any one of (1) to (23) above, which is for single mode. (25) An optical member having the optical waveguide according to any one of (1) to (24) above.

[0011] According to the present invention, it is possible to provide an optical waveguide with reduced transmission loss and low polarization dependent loss, and an optical member having such an optical waveguide.

[0012] Fig. 1 is a diagram showing an example of the cross-sectional shape of an optical waveguide according to one embodiment of the present invention, and Fig. 2 is a diagram showing an example of the taper angle of a core portion in an optical waveguide according to another embodiment of the present invention.

[0013] Hereinafter, an embodiment of the present invention (hereinafter sometimes referred to as the present embodiment) will be described in detail, but the following description is an example of an embodiment, and the present invention is not limited thereto. In the present invention, "(meth)acrylic" means "either one or both of acrylic and methacrylic." In the present invention, a numerical range expressed using "to" means a range including the numerical values ​​before and after "to" as the lower and upper limits. In the present invention, the weight average molecular weight means the weight average molecular weight (Mw) calculated in terms of polystyrene by gel permeation chromatography (GPC).

[0014] [Optical Waveguide] The optical waveguide of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of the cross-sectional shape of an optical waveguide of the present invention. In FIG. 1, the light propagation direction is from the front of the page to the back, or from the back of the page to the front. In other words, FIG. 1 is a diagram showing the cross-sectional shape of an optical waveguide in a direction perpendicular to the light propagation direction. The optical waveguide 10 shown in FIG. 1 has a core 20 and a cladding 30 having a lower refractive index than the core 20. The cladding 30 is composed of an undercladding 32 that contacts at least a portion of the core 20 (the lower portion of the core in FIG. 1), and an overcladding 31 that exists in a portion of the core 20 that is not in contact with the undercladding (the upper and left and right portions of the core in FIG. 1). In the present invention, an undercladding is in contact with a portion of the core, and an overcladding is in a portion of the core that is not in contact with the undercladding; however, the terms "undercladding" and "overcladding" are used merely for convenience. For example, in one aspect of the present invention, the part covering the lower part of the core may be referred to as the underclad and the part covering the upper part of the core as the overclad, and in another aspect, the two may be referred to in the reverse order.

[0015] In the optical waveguide 10, the refractive index difference between the core portion and the clad portion is preferably 0.005 or more and 0.05 or less. By reducing the refractive index difference between the core portion and the clad portion, single-mode waveguiding in the optical waveguide 10 becomes more likely. Furthermore, by providing a refractive index difference between the core portion and the clad portion, it is possible to reduce light scattering that occurs when the optical waveguide is bent. The lower limit of the refractive index difference is more preferably 0.01 or more. Furthermore, the upper limit is more preferably 0.03 or less. For example, in the case of a near-infrared single-mode optical signal, the refractive index difference is preferably 0.01 to 0.05, more preferably 0.01 to 0.04, and even more preferably 0.01 to 0.03.

[0016] In the cross-sectional shape of the optical waveguide shown in FIG. 1, L indicates the maximum length [μm] of the core portion 20 in the width direction when the direction of the line where the core portion 20 and the undercladding portion 32 meet is taken as the width direction, and H indicates the maximum length [μm] of the core portion 20 in the thickness direction when the direction perpendicular to the width direction is taken as the thickness direction (hereinafter, these may be simply referred to as L and H).

[0017] The optical waveguide of the first aspect of the present invention (hereinafter sometimes referred to as the optical waveguide of the first aspect) requires that the H / L be in the range of 0.4 to 3. When H / L is in the above range, the difference in transmission loss between orthogonal polarization and parallel polarization is reduced, and polarization dependent loss can be reduced. H / L is preferably 0.5 or more, more preferably 0.7 or more, and preferably 2 or less, more preferably 1.5 or less.

[0018] The optical waveguide of the first aspect may have a region where H is different, as long as H / L satisfies the above range. For example, H may be different between one end and the other end of the optical waveguide. Furthermore, H may be different between both ends of the optical waveguide and a middle portion in the light propagation direction of the core portion. The optical waveguide of the first aspect may have a region where L is different, as long as H / L satisfies the above range. For example, L may be different between one end and the other end of the optical waveguide. Furthermore, L may be different between both ends of the optical waveguide and a middle portion in the light propagation direction of the core portion.

[0019] In the optical waveguide of the second aspect of the present invention (hereinafter sometimes referred to as the optical waveguide of the second aspect), in the cross-sectional shape of the core portion perpendicular to the light propagation direction, the direction of the line where the core portion and the undercladding portion meet is the width direction, and the direction perpendicular to the width direction is the thickness direction. When the taper angle of the core portion is the angle formed by the tangent to the core side portion corresponding to half the length of the maximum length of the core portion in the thickness direction and the undercladding, the taper angle of the core portion must have a certain value. For example, if the core side portion (i) corresponding to half the length of the maximum length of the core portion in the thickness direction is a straight line, the taper angle of the core portion is the tangent to the core side portion, i.e., the angle formed by the core side portion (i) and the undercladding. If the core side portion (ii) corresponding to half the length of the maximum length of the core portion in the thickness direction is a curved line, the angle formed by the tangent to the core side portion (ii) and the undercladding is the taper angle of the core portion. In the cross-sectional shape of the core portion in a direction perpendicular to the light propagation direction, when the left and right taper angles of the core are different, in this embodiment, the smaller angle is taken as the taper angle of the core.

[0020] For example, in the cross-sectional shape of the optical waveguide shown in FIG. 2 , point A is taken on the side of the core portion 20 (i.e., the above-mentioned core side portion (i)) that corresponds to half the maximum length H of the core portion 20 in the thickness direction. The angle 40 formed by the line tangent to the core portion 20 at point A and the undercladding portion 32 is the taper angle of the left side of the core portion 20. Although not described in detail, if the taper angle of the left side differs from the taper angle of the right side of the core portion shown in FIG. 2 (the taper angle of the core portion formed by the tangent to the core side portion (ii) and the undercladding), as described above, the smaller angle is the taper angle of the core portion 20. In the optical waveguide of the second embodiment, the taper angle must be 50° or more and 130° or less. If the taper angle is outside the above range, the difference in transmission loss between orthogonal polarization and parallel polarization cannot be reduced, and polarization-dependent loss cannot be reduced. The lower limit of the taper angle is preferably 70° or more, more preferably 80° or more, and the upper limit is preferably 110° or less, more preferably 100° or less.

[0021] The optical waveguide of the second aspect may have a region where the maximum length H of the core portion in the thickness direction is different, as long as the taper angle satisfies the above range. For example, the maximum length H of the core portion in the thickness direction may be different between one end and the other end of the optical waveguide. Furthermore, the maximum length H of the core portion in the thickness direction may be different between both ends of the optical waveguide and an intermediate region of the core portion in the light propagation direction.

[0022] The optical waveguide of the second aspect may have portions with different L as long as the taper angle satisfies the above range. For example, L may be different between one end and the other end of the optical waveguide. Furthermore, L may be different between both ends of the optical waveguide and the intermediate portion in the light propagation direction of the core portion.

[0023] In the optical waveguides of the first and second aspects of the present invention (hereinafter sometimes referred to as the waveguides of both aspects), H is preferably 1.0 to 10 μm, and L is preferably 1.0 to 15 μm. When H and L are within the above ranges, light in higher modes at wavelengths of 1310 nm and 1550 nm tends to be less likely to propagate, and light in single mode tends to propagate. H is more preferably 3 to 10 μm, and even more preferably 3 to 8 μm. L is more preferably 3 to 10 μm, and even more preferably 3 to 8 μm.

[0024] The above H and L can be determined by cutting the optical waveguide and observing the cross-sectional shape of the core, for example, by using a scanning electron microscope (SEM).

[0025] In the case of an optical waveguide having a configuration in which a plurality of core portions are arranged in parallel with respect to a cladding portion, some core portions may exist whose maximum length in the thickness direction (H) and maximum length in the width direction (L) of the core portion do not satisfy the above ranges. Specific examples of core portions that do not satisfy the above ranges include core portions used for positioning when connecting optical waveguides.

[0026] The length of the undercladding portion 32 in the thickness direction is preferably 1 μm or more, more preferably 5 μm or more, and particularly preferably 10 μm or more. By making the length of the undercladding portion 32 in the thickness direction 1 μm or more, diffusion of light outside the core portion can be efficiently suppressed, and transmission loss can be reduced.

[0027] In order to achieve single-mode waveguiding within the core, it is preferable that overclad sections 31 exist above and on the left and right sides of the core section 20. If the overclad section 31 does not exist, air will act as the overclad, but the difference in refractive index between the core section and air is large, making single-mode waveguiding difficult.

[0028] When connecting an optical waveguide to a silica-based optical fiber, the smaller the difference in refractive index between the core of the optical waveguide and the core of the silica-based optical fiber, the more suppressed end face reflection at the connection portion. Generally, the refractive index of the core of a silica-based optical fiber at near-infrared wavelengths is about 1.4 to 1.5, and end face reflection tends to be suppressed when the refractive index of the core of the optical waveguide at near-infrared wavelengths is 1.40 to 1.50, more preferably 1.42 to 1.48. From the viewpoint of suppressing end face reflection of near-infrared light, the refractive index of the core at a wavelength of 1300 nm is preferably 1.400 or more and 1.520 or less, more preferably 1.420 or more and 1.500 or less, and particularly preferably 1.440 or more and 1.480 or less.

[0029] (Transmission Loss) One of the features of the optical waveguides of both embodiments is that the transmission loss is reduced, and the transmission loss, particularly at near-infrared wavelengths, is preferably 0.40 dB / cm or less, more preferably 0.35 dB / cm or less, even more preferably 0.32 dB or less, and still more preferably 0.30 dB / cm or less. The transmission loss is measured by the method described in the Examples below.

[0030] In the optical waveguides of both of these embodiments, the constituent materials of the core and clad are materials that produce a difference in refractive index such that the refractive index of the clad is lower than that of the core, and at least one of the core and clad must be made of a cured product obtained by curing a composition containing an organopolysiloxane (hereinafter sometimes simply referred to as "organopolysiloxane") having a polymerizable functional group, represented by the following formula [1]: (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (SiO ４／２ ) Ｑ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[1]

[0031] In the above formula [1], R １ ~R ５ , R ７ ~R １１ R are each independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of organic groups are present, they may be the same or different from one another, and 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0≦Q, 0<M2+D2+T2, 0<D1+D2+T1+T2+Q, M1+M2+D1+D2+T1+T2+Q=1.

[0032] In the general formula [1], the coefficients M1, M2, D1, D2, T1, T2, and Q represent the proportions (based on the number of moles) of each structure when M1 + M2 + D1 + D2 + T1 + T2 + Q = 1. In addition, in the general formula [1], the coefficients Y1 and Y2 represent the proportions (based on the number of moles) of each structure when M1 + M2 + D1 + D2 + T1 + T2 + Q = 1. １／２ R １１ ) and (O １／２ R６ ) relative content ratio (based on mole number).

[0033] In the general formula [1], the coefficients M1 and M2 represent the so-called M unit silicon (SiO １／２ Similarly, D1 and D2 represent the proportion of D unit silicon (SiO ２／２ ) (hereinafter sometimes simply referred to as "D units"), and T1 and T2 represent the proportion of T unit silicon (SiO ３／２ ) (hereinafter, sometimes simply referred to as "T units"), and Q represents the proportion of Q-unit silicon (SiO ４／２ M2, D2, and T2 represent the ratio of R to silicon atoms (hereinafter, sometimes simply referred to as "Q units"). ６ Y1 represents the proportion of a structure having a group selected from the group consisting of an organic group and a hydrogen atom, specifically an alkoxy group or a silanol group, which does not contain a polymerizable functional group, and Y2 represents the proportion of an organic group having a polymerizable functional group bonded to silicon.

[0034] 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0≦Q means that M1, D1, T1, Y1, Y2 and Q are each 0 or more, and may be 0, that is, the structural unit may not be present.

[0035] 0<M2+D2+T2 is a group in which R is attached to the silicon atom. ６ That is, the organopolysiloxane has at least one of M units, D units, and T units to which an organic group containing a polymerizable functional group is bonded. 0<D1+D2+T1+T2+Q means that the organopolysiloxane has at least one of D units, T units, and Q units. M1+M2+D1+D2+T1+T2+Q=1 means that the total proportion of M units, D units, T units, and Q units is 1.

[0036] <M2 + D2 + T2> In the organopolysiloxane represented by formula [1], if 0<M2 + D2 + T2, the organopolysiloxane contains a polymerizable functional group, making it possible to easily obtain a cured product using a composition containing a polymerization initiator, as described below. If the content of the polymerizable functional group is too low, poor curing may occur when preparing a cured product, and compatibility with other components added to the organopolysiloxane-containing composition, as described below, may be poor. From the above perspectives, it is preferable that 0.10≦M2 + D2 + T2, and more preferably that 0.12≦M2 + D2 + T2. Meanwhile, in the present invention, there are two embodiments for the upper limit of M2 + D2 + T2 in both aspects, as described below. In the first embodiment, if the ratio of M2+D2+T2 is too large, the content of polymerizable functional groups increases, and the crosslinking density of the cured product increases, making it prone to brittleness, so it is preferable that M2+D2+T2≦0.75, and more preferably that M2+D2+T2≦0.60. In the second embodiment, from the viewpoints of obtaining an organopolysiloxane with excellent heat resistance and a lower refractive index in the near-infrared wavelength region in addition to the above effects, it is preferable that M2+D2+T2≦0.25, and more preferably that M2+D2+T2≦0.20.

[0037] As described above, in the first embodiment, it is preferable that 0.10≦M2+D2+T2≦0.75, and it is even more preferable that 0.12≦M2+D2+T2≦0.60. In the second embodiment, it is preferable that 0<M2+D2+T2≦0.25, more preferably 0.10≦M2+D2+T2≦0.25, even more preferably 0.12≦M2+D2+T2≦0.25, still more preferably 0.12<M2+D2+T2≦0.25, and even more preferably 0.12<M2+D2+T2≦0.20.

[0038] <Q Units> Q units are the most oxidized form of silicon, and their inclusion in the structure of an organopolysiloxane can enhance the heat resistance of the cured product. Q units are also contained in quartz, and when an organopolysiloxane contains Q units, a composition containing the organopolysiloxane can be used to obtain a cured product having a refractive index close to that of the core material of a near-infrared single-mode silica-based optical fiber. The organopolysiloxane represented by formula [1] may or may not contain Q units, but from the viewpoint of improving the heat resistance of the cured product of the organopolysiloxane, it is preferable that the organopolysiloxane contains Q units, i.e., Q>0. On the other hand, from the viewpoint of improving the flexibility of the cured product of the organopolysiloxane, it is preferable that the organopolysiloxane does not contain Q units, i.e., Q=0.

[0039] In one embodiment of the present invention, when Q units are present, the coefficient Q is preferably greater than 0, more preferably 0.04 or greater, more preferably 0.10 or greater, and even more preferably 0.30 or greater. On the other hand, if the Q units are too many, the composition will become solid or its viscosity will increase, resulting in poor handleability. Therefore, the upper limit is usually 0.65 or less, more preferably 0.6 or less, and even more preferably 0.45 or less. As described above, when the organopolysiloxane represented by formula [1] contains Q units, its coefficient Q is preferably 0<Q≦0.65, more preferably 0.04≦Q≦0.6, and even more preferably 0.04≦Q≦0.45.

[0040] <D1 + D2 + T1 + T2 + Q> In the organopolysiloxane represented by formula [1], if 0 < D1 + D2 + T1 + T2 + Q, structural units other than M units can be introduced into the organopolysiloxane, which is advantageous from the viewpoint of curability and heat resistance after curing. 0.01 < D1 + D2 + T1 + T2 + Q is preferred, 0.1 < D1 + D2 + T1 + T2 + Q is more preferred, and 0.2 < D1 + D2 + T1 + T2 + Q is even more preferred. The upper limit is not particularly limited, but by definition is 1 or less. Furthermore, from the viewpoint of improving the heat resistance of the cured product of the organopolysiloxane, it is preferable that the relational expression "0 < D1 + D2 + T1 + T2 + Q" in formula [1] be replaced with "0 < Q", i.e., the organopolysiloxane contains Q units. This will be described later using formula [2].

[0041] <O １／２ R １１ > (O １／２ R １１ ) is a structure that does not have a polymerizable functional group and has a group selected from the group consisting of an organic group and a hydrogen atom, specifically an alkoxy group and / or a silanol group bonded to silicon. This structural unit allows the viscosity of the organopolysiloxane to be controlled and adjusted to a viscosity suitable for molding. The silanol group has the effect of increasing the viscosity, while the alkoxy group has the effect of decreasing the viscosity. When the content of alkoxy groups or silanol groups is low, the amount of highly mobile terminal groups is low and the siloxane skeleton becomes a rigid cage structure, resulting in an increased viscosity. Conversely, when the content of alkoxy groups or silanol groups is high, the amount of highly mobile terminal groups is high and the siloxane skeleton becomes a flexible random structure rather than a cage structure, resulting in a decreased viscosity.

[0042] <Coefficient Y1> (O １／２ R １１ The coefficient Y1, which indicates the content ratio of R １１From the definition of (I), it represents the total content of silanol groups and alkoxy groups in the organopolysiloxane. The range of coefficient Y1 is preferably 0 or more, more preferably 0.02 or more, even more preferably 0.025 or more, still more preferably 0.03 or more, and especially preferably 0.035 or more, from the viewpoint of the synthesis of organopolysiloxane and the viscosity adjustment required for the preparation of organopolysiloxane-containing compositions, which will be described later. On the other hand, from the viewpoint of storage stability and handleability, the upper limit of coefficient Y1 is preferably 0.25 or less, more preferably less than 0.25, even more preferably 0.2 or less, still more preferably 0.20 or less, especially preferably 0.15 or less, and particularly preferably 0.1 or less. As a preferred range in formula [1], 0.02≦Y1≦0.25 is preferred, 0.02≦Y1<0.25 is more preferred, 0.025≦Y1≦0.2 is even more preferred, 0.025≦Y1≦0.20 is even more preferred, 0.03≦Y1≦0.15 is particularly preferred, and 0.035≦Y1≦0.1 is particularly preferred. Y1 represents a relative value with respect to M1+M2+D1+D2+T1+T2+Q=1.

[0043] <Coefficient Y2> Y2 is the content of one or more organic groups containing a polymerizable functional group bonded to silicon via an oxygen atom in the organopolysiloxane. １／２ R ６ The coefficient Y2, which indicates the content ratio of the polymerizable functional group, is 0 or a positive value, preferably Y2 > 0.25, more preferably Y2 > 0.30, and even more preferably Y2 > 0.35. When Y2 > 0.25, compatibility with other resins is improved. Organic groups containing polymerizable functional groups are easily hydrolyzed and eliminated by water, which can lead to a high water absorption rate. Therefore, it is preferable to use them in a manner that is less susceptible to moisture. On the other hand, in environments affected by moisture, if Y2 is large, the cured product is likely to become brittle due to moisture, so Y2 < 0.4 is preferable, Y2 < 0.3 is more preferable, and Y2 < 0.2 is even more preferable. It is also preferable that Y2 is 0. Y2 represents a relative value to M1 + M2 + D1 + D2 + T1 + T2 + Q = 1.

[0044] <Coefficient M1> R containing a polymerizable functional group６ Although the M unit not having R is not an essential constituent of the organopolysiloxane, it may be included. ６ The proportion of M units not having M1 may be M1 > 0, and by substituting either the alkoxy groups or silanol groups of the organopolysiloxane with M units, the storage stability of the organopolysiloxane tends to be improved and the viscosity tends to be reduced. From the viewpoint of storage stability, the coefficient M1 is preferably 0.09 or more, and usually 0.6 or less, preferably 0.5 or less, and more preferably 0.4 or less.

[0045] <Coefficient D1> R containing a polymerizable functional group ６ Although D units not having R are not essential constituent elements of organopolysiloxanes, the inclusion of such units tends to impart toughness to the cured product. That is, from the viewpoint of imparting toughness to the cured product, D1≧0.2 is preferred, D1≧0.3 is more preferred, and D1≧0.4 is even more preferred. ６ If the content of D units not having

[0044] is too high, the heat resistance of the cured product tends to decrease. That is, from the viewpoint of suppressing the decrease in heat resistance of the cured product, D1 is preferably D1≦0.5, more preferably D1≦0.4, and even more preferably D1≦0.3.

[0046] <Coefficient T1> R containing a polymerizable functional group ６ Although T units not having R are not essential constituent elements of organopolysiloxanes, the inclusion of such units tends to improve compatibility with other components added to the organopolysiloxane-containing composition described below. From the viewpoint of improving compatibility with other components, T1≧0.2 is preferred, and T1≧0.3 is more preferred. ６ If the content of T units not having any of the formula (I) is too large, poor curing is likely to occur due to steric hindrance of the introduced organic group. Therefore, from the viewpoint of curability, T1≦0.5 is preferred, T1≦0.4 is more preferred, and T1≦0.3 is even more preferred.

[0047] From the above, it is preferable that the coefficients in the above formula [1] are 0<Q≦0.65, 0<M2+D2+T2≦0.75, 0.02≦Y1≦0.25, Y2<0.4, 0<M1≦0.6, D1≦0.7, T1≦0.5, and more preferably 0.04≦Q≦0.60, 0.10≦M2+D2+T2≦0.75, 0.025≦Y1≦0.20, Y2<0.3, 0.09≦M1≦0.5, D1≦0.6, T1≦0.4, and more preferably 0.04≦Q≦0.45, 0.12≦M2+D2+T2≦0.6, 0.03≦Y1≦0.15, Y2<0.2, 0.09≦M1≦0.4, It is more preferable that D1≦0.3 and T1≦0.3.

[0048] <R ６ > R ６ is one or more organic groups containing a polymerizable functional group. The polymerizable functional group of the organopolysiloxane is a reactive functional group that does not substantially react during the preparation of the organopolysiloxane but reacts upon application of external energy, resulting in crosslinking or chain extension between organopolysiloxane molecules, resulting in high molecular weight. Examples of external energy include light, heat, and electron beams, and these may be used in combination. When light (active energy rays) is used as the external energy, it is preferable to perform exposure in a state in which the organopolysiloxane and a photopolymerization initiator coexist. Furthermore, by selectively irradiating only the desired portions with active energy rays in the exposure step, only the exposed portions can be made high molecular weight, and the unexposed portions can be dissolved and removed in a developer. If necessary, external energy such as active energy rays or heat can be applied after exposure and development to further increase the molecular weight.

[0049] Specific examples of polymerizable functional groups include vinyl groups, allyl groups, allyloxy groups, methacryloyl(oxy) groups, acryloyl(oxy) groups, vinyloxy groups, trifluorovinyl groups, trifluorovinyloxy groups, ethynyl groups, 1-oxocyclopenta-2,5-dien-3-yl groups, cyano groups, alkoxysilyl groups, diarylhydroxymethyl groups, hydroxyfluorenyl groups, oxirane groups, and epoxy groups. In terms of high reactivity and the ability to obtain high crosslinking density, vinyl groups, methacryloyl(oxy) groups, acryloyl(oxy) groups, trifluorovinyloxy groups, ethynyl groups, oxirane groups, and epoxy groups are preferred, with methacryloyl(oxy) groups or acryloyl(oxy) groups being more preferred, and methacryloyl(oxy) groups being most preferred. The term "methacryloyl(oxy) group" refers to a methacryloyl group or a methacryloyloxy group. The same applies to an acryloyl(oxy) group.

[0050] In both of these embodiments, specifically, R ６ R may contain a polymerizable alkenyl group as the polymerizable functional group. Examples of the polymerizable alkenyl group include those having an acryloyl group, a methacryloyl group, a vinyl group, a styryl group, etc. ６ A preferred example of the group is an organic group containing at least one functional group selected from the group represented by the following formulas [i] to [iv] in one molecule.

[0051] (In the above formula, * indicates a bond.)

[0052] More preferably, R ６ has at least one functional group selected from the group consisting of an acryloyloxypropyl group, an acryloyloxyoctyl group, a methacryloyloxypropyl group, and a methacryloyloxyoctyl group in one molecule, and among these, it is particularly preferred that the compound has an acryloyloxypropyl group and / or a methacryloyloxypropyl group in one molecule.

[0053] In formulas [ii] and [iv], X is a divalent organic group and may have a branched structure and / or a cyclic structure. In addition to carbon and hydrogen, X may contain any one selected from the group consisting of oxygen, nitrogen, phosphorus, sulfur, and halogen. When X is bonded to a silicon atom, the atom at the end of X and directly bonded to the silicon is preferably a carbon atom. When X is bonded to an oxygen atom directly bonded to the silicon, the atom at the end of X and directly bonded to the oxygen atom is preferably a carbon atom. For example, a divalent hydrocarbon group having 1 to 20 carbon atoms, which may have a branched structure or a cyclic structure, or a polyalkylene glycol is preferably used.

[0054] In the organopolysiloxane represented by formula [1], the units constituting the M unit, D unit, and T unit do not all need to be the same. For example, the unit (R １ R ２ R ３ SiO １／２ ), for example, a certain R １ is a hydrogen atom, and a certain R １ may have a different structure, such as a methyl group. This is also true for other R and X.

[0055] <R １ ~R ５ , R ７ ~R １１ > R １ ~R ５ , R ７ ~R １１ R are each independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ５ , R ７ ~R １１is an organic group, it is preferably an organic group having 1 to 20 carbon atoms, specifically, it is preferably a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, or an aromatic ring group having 6 to 20 carbon atoms, more specifically, it is preferably an alkyl group such as a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, sec-butyl group, tert-butyl group, octyl group, or cyclohexyl group, or a polyether group such as a polyalkylene glycol group, and particularly preferably a methyl group.

[0056] The organopolysiloxane having a polymerizable alkenyl group is preferably represented by the following formula [2]: (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (SiO ４／２ ) Ｑ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[2]

[0057] In the general formula [2], the coefficients M1, M2, D1, D2, T1, T2, and Q represent the proportions (based on the number of moles) of each structure when M1 + M2 + D1 + D2 + T1 + T2 + Q = 1. In addition, in the general formula [2], the coefficients Y1 and Y2 represent the proportions (based on the number of moles) of each structure when M1 + M2 + D1 + D2 + T1 + T2 + Q = 1. １／２ R １１ ) and (O １／２ R ６) relative content ratio (based on mole number).

[0058] The organopolysiloxane having a polymerizable alkenyl group represented by formula [2] is an organopolysiloxane in which 0<Q. That is, it is characterized by having Q units. The presence of Q units can improve the heat resistance of the cured organopolysiloxane. Except for Q=0, the possible ranges of the coefficients M1, M2, D1, D2, T1, T2, and Q, including preferred combinations, are as described in formula [1] above. The structural units represented by each coefficient are also as described in formula [1] above.

[0059] The organopolysiloxane having a polymerizable functional group is preferably represented by the following formula [3]: (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[3]

[0060] In the above formula [3], R １ ~R ５ , R ７ ~R １１ R are each independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R１０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of groups are present, they may be the same or different, and 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0<M2+D2+T2, 0<D1+D2+T1+T2, M1+M2+D1+D2+T1+T2=1.

[0061] Formula [3] represents an organopolysiloxane in which the coefficient Q in formula [1] is 0, i.e., does not contain any Q units. １ ~R １１ are the same as in formula [1], and preferred groups are also the same. M1, M2, D1, D2, T1, T2, Y1, and Y2 are also the same as in formula [1], and preferred ranges of each coefficient are also the same.

[0062] <D1+D2+T1+T2> In the organopolysiloxane represented by formula [3], if D1+D2+T1+T2 is 0<D1+D2+T1+T2, a structural unit other than the M unit can be introduced into the organopolysiloxane, which is advantageous from the viewpoint of curability and heat resistance after curing. D1+D2+T1+T2 is preferably 0.01<D1+D2+T1+T2, more preferably 0.1<D1+D2+T1+T2, and even more preferably 0.2<D1+D2+T1+T2. There is no particular upper limit, and by definition it is 1 or less.

[0063] From the viewpoint of introducing flexible moieties into the organopolysiloxane and improving the crack resistance of the cured product, it is preferable that 0<D1+D2. D1+D2≧0.05 is more preferable, D1+D2≧0.1 is even more preferable, and D1+D2>0.1 is even more preferable. Furthermore, from the viewpoint of suppressing the thermal expansion of the cured product of the organopolysiloxane, D1+D2≦0.9 is preferable, and D1+D2≦0.8 is even more preferable. Since D unit structures that do not have polymerizable alkenyl groups and do not become crosslinking points are more effective in imparting toughness, D2=0 may be acceptable within the above range of D1+D2. From the same viewpoint, it is also preferable that 0<D1, more preferably 0.1<D1, even more preferably 0.20≦D1, even more preferably 0.25≦D1, and particularly preferably 0.30≦D1. Although there is no particular upper limit for D1, it is preferable that D1≦0.80, more preferably D1≦0.75, and even more preferably D1≦0.70. By adjusting the values ​​of D1 and D2 within the above ranges, an optical waveguide produced from the organopolysiloxane tends to have reduced roughness at the end face when cut, light scattering is also suppressed, and connection loss tends to be reduced.

[0064] From the viewpoint of improving the heat resistance of the cured product of the organopolysiloxane, it is preferable that T1 + T2 be 0 < T1 + T2. It is more preferable that T1 + T2 be ≥ 0.05, and it is even more preferable that T1 + T2 be ≥ 0.1. From the viewpoint of suppressing cure shrinkage of the cured product of the organopolysiloxane, it is preferable that T1 + T2 be ≤ 0.9, and it is more preferable that T1 + T2 be ≤ 0.8.

[0065] That is, from the viewpoint of achieving both crack resistance and heat resistance in the cured product of the organopolysiloxane, it is preferable that 0<D1+D2 and 0<T1+T2.

[0066] From the above, the proportions in the above formula [3] are preferably 0<M2+D2+T2≦0.9, 0.02≦Y1≦0.25, Y2<0.4, 0<M1≦0.6, D1≦0.5, T1≦0.5, more preferably 0.10≦M2+D2+T2≦0.8, 0.025≦Y1≦0.20, Y2<0.3, 0.09≦M1≦0.5, D1≦0.4, T1≦0.4, and even more preferably 0.12≦M2+D2+T2≦0.6, 0.03≦Y1≦0.15, Y2<0.2, 0.09≦M1≦0.4, D1≦0.3, T1≦0.3.

[0067] The core and clad of the optical waveguide of the present invention can be obtained by curing a composition containing the organopolysiloxane having the polymerizable functional group described above. In addition, in order to prevent the refractive index of the cured product from increasing, it is also preferable to use an organopolysiloxane having a polymerizable functional group that does not contain an aromatic structure. The content of the aromatic group is as follows: １ H-NMR, ２９ This can be confirmed by Si-NMR. The phrase "not containing" an aromatic structure means that an NMR chart does not have a clear peak that can be identified as an aromatic group.

[0068] [Method for Producing Organopolysiloxane Having Polymerizable Functional Group] The method for producing the organopolysiloxane having a polymerizable functional group is not particularly limited as long as it can produce the organopolysiloxane represented by the above formula [1], formula [2], and formula [3]. For example, any of the following methods may be used: a method of condensing a disiloxane compound, a disilazane compound, and their hydrolysates, an alkoxysilane compound, and their hydrolysates, or partial hydrolyzed condensates, either singly or in combination; a method of condensing a chlorosilane compound, and their hydrolysates, or partial hydrolyzed condensates; a method of ring-opening polymerization of a cyclic siloxane compound; or chain polymerization such as anionic polymerization; or a combination of these methods may be used. Furthermore, the method for introducing the polymerizable functional group is not particularly limited, and any method may be used, such as a method of condensing an alkoxysilane compound, disiloxane compound, or disilazane compound having a polymerizable functional group, or a hydrolyzate or partial hydrolysis condensate thereof, either singly or in combination, or a method of converting a reactive organic group introduced into an organopolysiloxane into a polymerizable functional group by a chemical method, or a combination of these methods may be used. Examples of raw materials that can be used for producing an organopolysiloxane having a polymerizable functional group by hydrolysis condensation are given below.

[0069] (Source of M Units) Examples of sources of M units include trimethylsilanol, trimethylmethoxysilane, hexamethyldisiloxane, hexamethyldisilazane, dimethylsilanol, dimethylmethoxysilane, tetramethyldisiloxane, tetramethyldisilazane, dimethylvinylsilanol, dimethylvinylmethoxysilane, 1,3-divinyltetramethyldisiloxane, 1,3-divinyltetramethyldisilazane, dimethyl(meth)acryloyloxypropylsilanol, dimethyl(meth)acryloyloxypropylmethoxysilane, 1,3-di(meth)acryloyloxypropyl)tetramethyldisiloxane, dimethylglycidyloxypropylmethoxysilane, 1,3-bis(3-glycidyloxypropyl)tetramethyldisiloxane, 3-(meth)acryloyloxypropyldimethylsilanol, 3-(meth)acryloyloxypropyldimethylmethoxysilane, 1,3-bis((meth)acryloyloxypropyl) Examples of compounds that can be used include (trimethylsiloxane, methyldisiloxane, methoxytriphenylsilane, triphenylsilanol, 1,3-diphenyltetramethyldisiloxane, 1,3-diphenyltetramethyldisilazane, dimethylphenylsilanol, dimethylmethoxyphenylsilane, 1,4-bis(dimethylmethoxysilyl)benzene, 1,4-bis(dimethylethoxysilyl)benzene, 2-(3,4-epoxycyclohexyl)ethyldimethylmethoxysilane, 2-(3,4-epoxycyclohexyl)ethyldimethylethoxysilane, 3-glycidoxypropyldimethylmethoxysilane, 3-glycidoxypropyldimethylethoxysilane, and compounds containing a silanol hydroxyl group or an alkoxy group among the above-listed compounds, in which a halogen atom is bonded in place of the silanol hydroxyl group or the alkoxy group. Hexamethyldisiloxane is particularly suitable as a source of M units.

[0070] (D unit source) Examples of the D unit source include dimethyldisilanol, dimethyldimethoxysilane, diphenyldisilanol, diphenyldimethoxysilane, tetramethyldisiloxane, 3-(meth)acryloyloxypropyldimethoxymethylsilane, methyldimethoxyphenylsilane, diethoxymethylphenylsilane, methylphenyldisilanol, 1,4-bis(methyldimethoxysilyl)benzene, 1,4-bis(methyldiethoxysilyl)benzene, dimethoxy(methyl)(3,3,3-trifluoropropyl)silane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldiethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and compounds in which halogen is bonded in place of the silanol hydroxyl group or alkoxy group of the above-listed compounds, as well as polymers thereof. Dimethyldimethoxysilane is particularly preferred.

[0071] (T Unit Source) Examples of T unit sources include C trimethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane, propyltrimethoxysilane, hexyltrimethoxysilane, and decyltrimethoxysilane. １ ~C ２０Examples of the long-chain alkoxy group-modified trimethoxysilane include vinyltrimethoxysilane, phenyltrimethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane, 3-(meth)acryloyloxypropyltrimethoxysilane, 8-(meth)acryloyloxyoctyltrimethoxysilane, 1,4-bis(trimethoxysilyl)benzene, p-styryltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 8-glycidyloxyoctyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, and 3-glycidoxypropyltrimethoxysilane. In addition to these methoxysilane compounds, alkoxysilane compounds such as ethoxysilane, silanol compounds, chlorosilane compounds, hydrosilylsilane compounds, and polymers thereof can also be used. In particular, 3-methacryloyloxypropyltrimethoxysilane, 8-methacryloyloxyoctyltrimethoxysilane, 3-acryloyloxypropyltrimethoxysilane, 8-acryloyloxyoctyltrimethoxysilane, and decyltrimethoxysilane can be preferably used.

[0072] (Q Unit Source) Examples of Q unit sources include tetrachlorosilane, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane, tetrapropoxysilane, tetrabutoxysilane, tetrapentyloxysilane, tetraphenyloxysilane, trimethoxymonoethoxysilane, dimethoxydiethoxysilane, triethoxymonomethoxysilane, trimethoxymonopropoxysilane, monomethoxytributoxysilane, monomethoxytripentyloxysilane, monomethoxytriphenyloxysilane, dimethoxydipropoxysilane, tripropoxymonomethoxysilane, trimethoxymonobutoxysilane, dimethoxydibutoxysilane, triethoxymonopropoxysilane, diethoxydipropoxysilane, tributoxymonopropoxysilane, dimethoxymonoethoxymonobutoxysilane, Examples of suitable alkoxysilanes include silane, diethoxymonomethoxymonobutoxysilane, diethoxymonopropoxymonobutoxysilane, dipropoxymonomethoxymonoethoxysilane, dipropoxymonomethoxymonobutoxysilane, dipropoxymonoethoxymonobutoxysilane, dibutoxymonomethoxymonoethoxysilane, dibutoxymonoethoxymonopropoxysilane, and monomethoxymonoethoxymonopropoxymonobutoxysilane; aryloxysilanes; and tetramethoxysilane oligomers such as methyl silicate MS51, MS56, MS57, and MS60 manufactured by Mitsubishi Chemical Corporation, and tetraethoxysilane oligomers such as ethyl silicate oligomer ES40 and ES48 manufactured by Tama Chemicals Co., Ltd., with methyl silicate MS51 being particularly preferred. The above M, D, T, and Q unit sources can each be used in combination of one or more types.

[0073] As a catalyst for hydrolysis and condensation of these silicon raw materials, an acid catalyst, a base catalyst, or an inorganic salt can be used, and an acid catalyst is particularly preferably used. Examples of acid catalysts include hydrochloric acid, sulfuric acid, trifluoroacetic acid, acetic acid, methacrylic acid, acrylic acid, etc., and hydrochloric acid is particularly preferably used. Examples of base catalysts include ammonia, hexamethyldisilazane, triethylamine, tetraethylammonium hydroxide, diazabicycloundecene, potassium hydroxide, sodium hydroxide, barium hydroxide, potassium carbonate, sodium carbonate, etc., and potassium hydroxide is particularly preferred. Examples of inorganic salts include sodium chloride, potassium chloride, magnesium chloride, calcium chloride, sodium bromide, potassium bromide, magnesium bromide, calcium bromide, etc., and sodium chloride is particularly preferred.

[0074] Examples of the solvent that can be used in the hydrolysis condensation reaction include tetrahydrofuran, toluene, methanol, ethanol, isopropanol, hexane, and heptane. Tetrahydrofuran is particularly preferred. Depending on the solubility of the product, two or more solvents may be used. A mixed solution of toluene and methanol, or a mixed solution of tetrahydrofuran and methanol is particularly preferred.

[0075] The alkoxy groups and silanol groups remaining without hydrolysis and condensation may be substituted with an organic acid or alcohol, as necessary. Examples of the organic acid include acetic acid, acrylic acid, and methacrylic acid. Examples of the alcohol that do not contain a polymerizable alkenyl group include methanol, ethanol, propanol, butyl alcohol, pentanol, hexanol, heptanol, and structural isomers thereof. Examples of the alcohol that contains a polymerizable alkenyl group include 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate, with 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate being preferred from the viewpoint of stability.

[0076] If the organopolysiloxane has a rigid structure such as a complete cage silsesquioxane, the cured product will be hard and brittle, so it is preferable that the organopolysiloxane does not have a complete cage structure. As long as it is not a complete cage silsesquioxane, for example, it may contain a random structure or a ladder structure as a higher-order structure, as long as the effects of the present invention are not impaired.

[0077] <Water> The amount of water used for hydrolysis is preferably 0.5 equivalents or more, more preferably 0.8 equivalents or more, and even more preferably 1.1 equivalents or more, relative to the total amount of alkoxy groups contained in the MDTQ unit source. The water is not particularly limited, and may be water contained in commercially available hydrochloric acid or the like, or water purified by distillation or ion exchange resin.

[0078] As described above, in both embodiments, at least one of the core and clad must be composed of a cured product obtained by curing the organopolysiloxane-containing composition represented by the above formula [1]. However, the core and clad may be composed of other materials as long as the effects of the present invention are not impaired. For example, various resin materials can be used, including organic-inorganic hybrid materials such as organopolysiloxanes having polymerizable functional groups, acrylic resins, methacrylic resins such as polymethyl methacrylate (PMMA), epoxy resins, oxetane resins, phenoxy resins, benzocyclobutene resins, norbornene resins, fluorine-containing resins, silicone resins, phenolic resins, polyester resins, polycarbonate resins, polystyrene resins, polyamide resins, polyimide resins, polyimide resins such as poly(imide-isoindoloquinazolinedionimide) resins, polyetherimide resins, polyetherketone resins, and polyesterimide resins, polybenzoxazole resins, and polysilanes. Among these materials, materials that have high transparency in the near-infrared wavelength band and high heat resistance can be suitably used as materials for the core and clad. However, in both of the present embodiments, it is preferred that both the core and clad be made of a cured product obtained by curing an organopolysiloxane-containing composition represented by formula [1].

[0079] [Composition Containing Organopolysiloxane Having Polymerizable Functional Group] The composition containing an organopolysiloxane having a polymerizable functional group (hereinafter, sometimes simply referred to as "organopolysiloxane-containing composition") of the present invention is used to form an optical waveguide. As described above, the composition is preferably a composition containing an organopolysiloxane having a polymerizable functional group, and more preferably a composition containing an organopolysiloxane having a polymerizable alkenyl group. In addition to the organopolysiloxane described above, the composition may contain a monofunctional polymerizable alkenyl compound, a polyfunctional polymerizable alkenyl compound, and / or an alkenyl polymer, etc., within a range that does not impair the properties of the cured product obtained from the composition, as described below.

[0080] Furthermore, a polymerization initiator can be added to polymerize and cure the organopolysiloxane and polymerizable alkenyl compound. While it is possible to cure organopolysiloxanes or organopolysiloxane-containing resin compositions by electron beam irradiation or the like without using a polymerization initiator, a preferred embodiment of the organopolysiloxane-containing composition of the present invention contains at least a polymerization initiator in addition to the organopolysiloxane described above. Other components may also be added, such as sensitizers, chain transfer agents, antioxidants, UV absorbers, light stabilizers, leveling agents, rheology modifiers, adhesion aids such as silane coupling agents, dyes, defoamers, other components, and solvents, to the extent that they do not impair the properties of the cured product obtained from the composition (described below). Components that may be included in the organopolysiloxane-containing composition are described below.

[0081] <Monofunctional Polymerizable Alkenyl Compound> Specific examples of the monofunctional polymerizable alkenyl compound include (meth)acrylates containing a carboxy group, such as (meth)acrylic acid, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, 2-(meth)acryloyloxyethyl phthalate, and 2-(meth)acryloyloxyethyl hexahydrophthalate; (meth)acrylates having a hydroxyl group, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 6-hydroxyhexyl (meth)acrylate; Alkyl (meth)acrylates such as methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, pentyl (meth)acrylate, heptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate; (meth)acrylates containing an alicyclic structure, such as cyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, 2-dicyclopentenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentanyl (meth)acrylate, adamantyl (meth)acrylate, and 4-tert-butylcyclohexyl (meth)acrylate;(Meth)acrylates containing an aromatic ring structure such as phenyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, phenoxypolyethylene glycol (meth)acrylate, nonylphenoxypolyethylene glycol (meth)acrylate, phenoxypolypropylene glycol (meth)acrylate, phenylphenyl (meth)acrylate, phenylphenoxyethyl (meth)acrylate, phenoxybenzyl (meth)acrylate, phenylbenzyl (meth)acrylate, naphthyl (meth)acrylate, and (1-naphthyl)methyl (meth)acrylate; (meth)acrylates containing a heterocyclic structure such as tetrahydrofurfuryl (meth)acrylate, glycidyl (meth)acrylate, and (meth)acryloylmorpholine; alkoxy (meth)acrylates such as methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, and butoxyethyl (meth)acrylate; Examples include 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 2-(meth)acryloyloxyethyl acid phosphate, trifluoroethyl (meth)acrylate and heptadecafluorodecyl (meth)acrylate, and 2-(meth)acryloyloxyethyl isocyanate; styrene derivatives such as styrene, α-methylstyrene, 2-vinylpyridine, 4-vinylpyridine, 1,1-diphenylethylene, and aromatic ring hydrogen-substituted derivatives thereof; and vinyl compounds such as vinyl acetate, vinyl octanoate, vinyl decanoate, vinyl hexanoate, acrylonitrile, and vinyl benzoate. It is preferable to use compounds that do not contain an aromatic structure, as this increases the refractive index of the cured product.

[0082] <Polyfunctional Polymerizable Alkenyl Compound> Specific examples of the polyfunctional polymerizable alkenyl compound include alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, butylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, 1,10-decanediol di(meth)acrylate, and neopentyl glycol di(meth)acrylate; polyalkylene glycol di(meth)acrylates such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, and polybutylene glycol di(meth)acrylate; Di(meth)acrylates containing an alicyclic structure such as cyclohexanedimethanol di(meth)acrylate, tricyclodecanedimethanol di(meth)acrylate, ethoxylated hydrogenated bisphenol A di(meth)acrylate, propoxylated hydrogenated bisphenol A di(meth)acrylate, and adamantanediol di(meth)acrylate; bifunctional (meth)acrylates such as polycarbonate diol di(meth)acrylate, polyester diol di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate, propoxylated bisphenol A di(meth)acrylate, 9,9-bis(4-acryloyloxyethoxyphenyl)fluorene, and polyurethane di(meth)acrylate; Examples of suitable monomers include trifunctional (meth)acrylates such as trimethylolpropane tri(meth)acrylate, ethoxylated isocyanuric acid tri(meth)acrylate, and ε-caprolactone-modified tris((meth)acryloxyethyl)isocyanurate; tetrafunctional (meth)acrylates such as ditrimethylolpropane tetra(meth)acrylate; pentafunctional (meth)acrylates such as dipentaerythritol penta(meth)acrylate; polyfunctional monomers such as hexafunctional (meth)acrylates such as dipentaerythritol hexa(meth)acrylate; 1,4-divinylbenzene, and 1,3-divinylbenzene. It is preferable to use a monomer that does not contain an aromatic structure, as this increases the refractive index of the cured product.

[0083] <Alkenyl Polymer> An alkenyl polymer is a polymer containing 50% by mass or more of alkenyl monomer units in its composition. In this specification, "unit" refers to a repeating unit constituting a polymer. The alkenyl polymer may be monofunctional or polyfunctional. Furthermore, it is preferable to use an alkenyl polymer that does not contain an aromatic structure, as this increases the refractive index of the cured product and makes the cured product brittle. The alkenyl polymer may contain one or more types of alkenyl monomer units. The polymerization method for obtaining the alkenyl polymer is not particularly limited, and can be, for example, a known method such as solution polymerization, suspension polymerization, emulsion polymerization, or partial polymerization. In the present invention, suspension polymerization is preferred because it is relatively easy to control the polymerization reaction and separate the produced polymer.

[0084] The alkenyl polymer may be modified by introducing a double bond-containing functional group, such as a (meth)acryloyl group or a vinyl group, into the side chain by chemical modification. Examples of chemical modification methods include the reaction of a carboxy group with a glycidyl group and the reaction of a hydroxyl group with an isocyanate group. When the reaction of a carboxy group with a glycidyl group is used as the chemical modification method, for example, an alkenyl polymer containing an alkenyl monomer unit having a carboxy group is produced, and the resulting alkenyl polymer is reacted with a compound having a glycidyl group and a double bond, such as glycidyl (meth)acrylate.

[0085] In order to shorten the reaction time, it is preferable to use a reaction catalyst for the reaction of an alkenyl polymer containing an alkenyl monomer unit having a carboxy group with a compound having a glycidyl group and a double bond. Examples of the reaction catalyst include quaternary ammonium salts such as tetrabutylammonium bromide, quaternary phosphonium salts such as ethyltriphenylphosphonium bromide, and phosphine compounds such as triphenylphosphine. Quaternary ammonium salts are particularly preferred because they are less likely to discolor the organopolysiloxane-containing composition of this embodiment.

[0086] The weight-average molecular weight (Mw) of the alkenyl polymer is preferably 5,000 to 500,000, and more preferably 10,000 to 200,000. When the weight-average molecular weight is 5,000 or more, the strength of the cured product is improved. When the weight-average molecular weight is 500,000 or less, the viscosity of the organopolysiloxane-containing composition of this embodiment is reduced, thereby improving workability.

[0087] <Polymerization initiator> Examples of the polymerization initiator include a photopolymerization initiator, a thermal polymerization initiator, a peroxide used in redox polymerization, etc. The type of polymerization initiator can be appropriately selected depending on the polymerization method.

[0088] (Photopolymerization initiator) The photopolymerization initiator is a radical polymerization initiator used for photopolymerization. Specific examples of the photopolymerization initiator include benzophenone-type compounds such as benzophenone, 4-methylbenzophenone, 2,4,6-trimethylbenzophenone, methyl 2-benzoylbenzoate, and 4-phenylbenzophenone; anthraquinone-type compounds such as tert-butylanthraquinone and 2-ethylanthraquinone; 2-hydroxy-2-methyl-1-phenylpropan-1-one, oligo{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone}, benzyl dimethyl ketal, and 1-methyl-2-methyl-1-phenylpropan-1-one. alkylphenone compounds such as 4-hydroxycyclohexyl phenyl ketone, benzoin methyl ether, 2-methyl-[4-(methylthio)phenyl]-2-morpholino-1-propanone, and 2-hydroxy-1-{4-[4-(2-hydroxy-2-methylpropionyl)benzyl]phenyl}-2-methylpropan-1-one; thioxanthone compounds such as 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone, diethylthioxanthone, and isopropylthioxanthone; 2,4,6-trimethyl-4'-dimethylamino-4'-morpholinobutyrophenone, diethylthioxanthone, and isopropylthioxanthone; Acylphosphine oxide compounds such as methylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; phenylglyoxylate compounds such as phenylglyoxylic acid methyl ester; N-acetoxy-N-{4-acetoxyimino-4-[9-ethyl-6-(o-toluoyl)-9H-carbazol-3-yl]butane-2- yl}acetamide, N-acetoxy-N-{3-(acetoxyimino)-3-[9-ethyl-6-(1-naphthoyl)-9H-carbazol-3-yl]-1-methylpropyl}acetamide, 4-acetoxyimino-5-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-5-oxopentanoate, methyl 4-acetoxyimino-5-oxo-5-(4-(phenylthio)phenyl)pentanoate, and other oxime ester compounds, as well as combinations thereof.

[0089] Among these, alkylphenone-type compounds are preferred in terms of their ability to suppress discoloration of the cured product, with 2-hydroxy-2-methyl-1-phenylpropan-1-one and 1-hydroxycyclohexyl phenyl ketone being more preferred. Furthermore, acylphosphine oxide-type compounds are preferred in terms of their ability to facilitate sufficient curing deep into the cured product, with 2,4,6-trimethylbenzoyldiphenylphosphine oxide and methyl 4-acetoxyimino-5-oxo-5-(4-(phenylthio)phenyl)pentanoate being more preferred in terms of their ability to suppress discoloration of the cured product. Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, which has high sensitivity to light at longer wavelengths, is more preferred. From the viewpoint of high reactivity to light with a wavelength around 365 nm, 2-benzyl-2-dimethylamino-4'-morpholinobutyrophenone is also preferred. These photopolymerization initiators may be used alone, or two or more may be used in combination.

[0090] When the organopolysiloxane-containing composition of the present invention is cured by photopolymerization to obtain a cured product, the wavelength of the light irradiated onto the organopolysiloxane-containing composition is not particularly limited, but ultraviolet light with a wavelength of 200 to 500 nm is preferred. Specific examples of ultraviolet light sources include ultra-high pressure mercury lamps, high-pressure mercury lamps, metal halide lamps, high-power metal halide lamps, UV-LED lamps, chemical lamps, and black lights. After photopolymerization of the organopolysiloxane-containing composition, an aftercure may be further performed. This aftercure can reduce the amount of unreacted polymerizable alkenyl groups remaining in the cured product, thereby further increasing the strength of the cured product. Examples of aftercure conditions include a temperature of 50°C to 200°C for several tens of seconds to 60 minutes, or a temperature of 80°C to 150°C for several tens of seconds to 60 minutes.

[0091] (Thermal Polymerization Initiator) The thermal polymerization initiator is a radical polymerization initiator used in thermal polymerization. Examples of the thermal polymerization initiator include organic peroxides and azo compounds. Specific examples of organic peroxides include ketone peroxides such as methyl ethyl ketone peroxide; peroxyketals such as 1,1-di(tert-hexylperoxy)-3,3,5-trimethylcyclohexane, 1,1-di(tert-hexylperoxy)cyclohexane, and 1,1-di(tert-butylperoxy)cyclohexane; hydroperoxides such as 1,1,3,3-tetramethylbutyl hydroperoxide, cumene hydroperoxide, and p-menthane hydroperoxide; dicumyl peroxide, di-tert-butyl peroxide, etc. diacyl peroxides such as dilauroyl peroxide and dibenzoyl peroxide; peroxydicarbonates such as di(4-tert-butylcyclohexyl)peroxydicarbonate and di(2-ethylhexyl)peroxydicarbonate; and peroxyesters such as tert-butylperoxy-2-ethylhexanoate, tert-hexylperoxyisopropyl monocarbonate, tert-butylperoxybenzoate, and 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate.

[0092] Specific examples of azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 1,1'-azobis-1-cyclohexanecarbonitrile, dimethyl-2,2'-azobisisobutyrate, 4,4'-azobis-4-cyanovaleric acid, and 2,2'-azobis-(2-amidinopropane) dihydrochloride.

[0093] These thermal polymerization initiators may be used alone or in combination of two or more. Organic peroxides are preferred as thermal polymerization initiators because they are less likely to produce bubbles in the cured product. Considering the balance between the curing time and pot life of the organopolysiloxane-containing composition, the 10-hour half-life temperature of the organic peroxide is preferably 35 to 80°C, more preferably 40 to 75°C, and even more preferably 45 to 70°C. If the 10-hour half-life temperature is 35°C or higher, the organopolysiloxane-containing composition is less likely to gel at room temperature, resulting in a good pot life. On the other hand, if the 10-hour half-life temperature is 80°C or lower, the curing time of the organopolysiloxane-containing composition can be shortened.

[0094] Examples of such organic peroxides include 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, tert-butylperoxy-2-ethylhexanoate, and di(4-tert-butylcyclohexyl)peroxydicarbonate. Commercially available 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate includes, for example, Perocta O (trade name, manufactured by NOF Corporation, 10-hour half-life temperature: 65.3°C). Commercially available tert-butylperoxy-2-ethylhexanoate includes, for example, Perbutyl O (trade name, manufactured by NOF Corporation, 10-hour half-life temperature: 72.1°C). Commercially available di(4-tert-butylcyclohexyl)peroxydicarbonate includes, for example, Peroyl TCP (trade name, manufactured by NOF Corporation, 10-hour half-life temperature: 40.8°C).

[0095] When an organopolysiloxane-containing composition is cured by thermal polymerization to obtain a cured product, the curing conditions are not particularly limited. However, from the viewpoint of easily obtaining a resin for optical components with reduced coloration, the curing temperature is preferably 40 to 200°C, more preferably 60 to 150°C. The curing time (heating time) varies depending on the curing temperature, but is preferably 1 to 120 minutes, more preferably 1 to 60 minutes. After thermally polymerizing the organopolysiloxane-containing composition, it is preferable to further perform after-cure. Examples of after-cure conditions include a temperature of 50°C to 200°C for several tens of seconds to 60 minutes, or a temperature of 80°C to 150°C for several tens of seconds to 60 minutes.

[0096] (Redox Polymerization) Redox polymerization typically uses a redox polymerization initiator. A redox polymerization initiator is a polymerization initiator that uses a peroxide and a reducing agent in combination. Examples of peroxides used in redox polymerization include dibenzoyl peroxide and hydroperoxide. These peroxides may be used alone or in combination of two or more. When using the above-mentioned peroxides as redox polymerization initiators, examples of combinations with reducing agents include the following: (1) A combination of dibenzoyl peroxide (peroxide) with an aromatic tertiary amine (reducing agent) such as N,N-dimethylaniline, N,N-dimethyl-p-toluidine, or N,N-bis(2-hydroxypropyl)-p-toluidine. (2) A combination of a hydroperoxide (peroxide) with a metal soap (reducing agent). (3) A combination of a hydroperoxide (peroxide) with a thiourea (reducing agent).

[0097] When an organopolysiloxane-containing composition is cured by redox polymerization to obtain a cured product, the use of a redox polymerization initiator allows for curing at room temperature (5 to 40°C). A curing temperature of 15 to 40°C is preferred, as this reduces the amount of unreacted (meth)acryloyl groups remaining in the resulting cured product and further increases the strength of the cured product. Because the organopolysiloxane-containing composition is less likely to gel and can be handled stably, a preferred method involves dissolving a reducing agent in the organopolysiloxane-containing composition in advance and then adding a peroxide to the composition to carry out curing. When curing the organopolysiloxane-containing composition, it is preferable to cure the organopolysiloxane-containing composition in a sealed state to prevent curing inhibition by oxygen. Examples of sealing methods include sandwiching the organopolysiloxane-containing composition between glass or PET film.

[0098] <Chain Transfer Agent> When the curing reaction of an organopolysiloxane-containing composition is carried out in air, oxygen traps active radicals as peroxide radicals, inhibiting polymerization. However, by adding a chain transfer agent that donates hydrogen, polymerization inhibition by oxygen can be suppressed. Examples of the chain transfer agent include thiol compounds such as methyl mercaptoacetate, methyl 3-mercaptopropionate, 2-ethylhexyl 3-mercaptopropionate, 3-methoxybutyl 3-mercaptopropionate, n-octyl 3-mercaptopropionate, stearyl 3-mercaptopropionate, 1,4-bis(3-mercaptopropionyloxy)butane, 1,4-bis(3-mercaptobutyryloxy)butane, trimethylolethane tris(3-mercaptopropione), and the like. ester), trimethylolethane tris(3-mercaptobutyrate), trimethylolpropane tris(3-mercaptopropionate), trimethylolpropane tris(3-mercaptobutyrate), pentaerythritol tetrakis(3-mercaptopropionate), pentaerythritol tetrakis(3-mercaptobutyrate), dipentaerythritol hexakis(3-mercaptopropionate), dipentaerythritol hexakis(3-mercaptobutyrate), Mercaptocarboxylic acid esters such as tris[2-(3-mercaptopropionyloxy)ethyl]isocyanurate and tris[2-(3-mercaptobutyryloxy)ethyl]isocyanurate; alkyl thiols such as ethanethiol, 2-methylpropane-2-thiol, n-dodecanethiol, 2,3,3,4,4,5-hexamethylhexane-2-thiol (tert-dodecanethiol), ethane-1,2-dithiol, propane-1,3-dithiol, and benzylthiol aromatic thiols such as benzenethiol, 3-methylbenzenethiol, 4-methylbenzenethiol, naphthalene-2-thiol, pyridine-2-thiol, benzimidazole-2-thiol, and benzothiazole-2-thiol; mercaptoalcohols such as 2-mercaptoethanol and 4-mercapto-1-butanol; and silane-containing thiols such as 3-(trimethoxysilyl)propane-1-thiol and 3-(triethoxysilyl)propane-1-thiol.Among these, from the viewpoint of the reactivity and storage stability of the curable composition, it is preferable to use a secondary thiol compound. When a chain transfer agent is added, the chain transfer agent may be used alone or in combination of two or more. The amount added is 0.01 to 20 parts by mass, more preferably 0.1 to 10 parts by mass, and even more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the total amount of polymerizable components. When two or more types are used in combination, the total amount of chain transfer agents falls within the above range.

[0099] <Solvent> A solvent can be added to the organopolysiloxane-containing composition for the purpose of diluting it. The type of solvent is not particularly limited as long as it does not impair the physical properties required for the cured product of the organopolysiloxane-containing composition. Examples of solvents include aromatic hydrocarbons (e.g., toluene, xylene, ethyl benzoate, ethylbenzene, benzyl alcohol), ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, diacetone alcohol), esters (e.g., methyl acetate, ethyl acetate, butyl acetate, sec-butyl acetate, methoxybutyl acetate, amyl acetate, normal propyl acetate, ethyl lactate, methyl lactate, butyl lactate, propylene glycol monomethyl ether acetate, γ-butyrolactone), and ethers (e.g., For example, isopropyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monobutyl ether, 1,4-dioxane, methyl tert-butyl ether, tetrahydrofuran), alcohols (for example, methanol, ethanol, normal propanol, isopropanol, butanol, sec-butanol, tert-butanol, normal pentanol), halogenated solvents (for example, methylene chloride, trichloroethylene, tetrachloroethylene, bromopropane, chloroform), and others (for example, dimethyl sulfoxide, N,N-dimethylformamide, water), and two or more types of solvents may be used.

[0100] The content of the solvent in the organopolysiloxane-containing composition is not particularly limited as long as it does not impair the physical properties required of the cured product of the organopolysiloxane-containing composition, but when it is desired to reduce the viscosity while keeping the volatile content low, it is preferably more than 0% by mass and not more than 25% by mass of the entire organopolysiloxane-containing composition. Furthermore, when a thin-film cured product is to be obtained, it is preferably 75% by mass or more and less than 100% by mass of the entire composition.

[0101] (Antioxidant) The organopolysiloxane-containing composition preferably further contains an antioxidant. By including an antioxidant in the organopolysiloxane-containing composition, coloration due to heat, such as heating during soldering of a cured product or heat generation in a device, can be suppressed. Specific examples of antioxidants include phenols such as 2,6-di-tert-butylphenol, 2,6-di-tert-butyl-p-cresol, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, tetrakis-[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], and 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]. Examples of such antioxidants include phosphorus-based antioxidants such as triphenyl phosphite, trisisodecyl phosphite, tristridecyl phosphite, tris(2,4-di-tert-butylphenyl)phosphite, and tetra(C12-15 alkyl)-4,4'-isopropylidene diphenyl diphosphite; and sulfur-based antioxidants such as dilauryl-3,3'-thiodipropionate, ditridecyl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, distearic-3,3'-thiodipropionate, and pentaerythritol tetrakis(β-laurylthiopropionate). These antioxidants may be used alone or in combination of two or more.

[0102] (Other Components) The organopolysiloxane-containing composition of the present invention may contain other components such as a filler, a cure regulator, a viscosity modifier, etc. These components may be contained as appropriate to the extent that they do not affect the transmission loss, heat resistance, or refractive index of the cured product.

[0103] [Curing of Organopolysiloxane-Containing Composition] With regard to the cured product obtained by curing the organopolysiloxane-containing composition described above with heat or light, the curing conditions for the organopolysiloxane-containing composition are not particularly limited, and the composition can be cured under conditions that are appropriately employed for curing silicone resins, depending on the type of polymerization initiator, etc.

[0104] [Properties of the Cured Product] When the organopolysiloxane-containing composition of the present invention is cured as described above, a cured product having the following properties can be obtained.

[0105] (Refractive index) The refractive index of the cured product can be controlled by changing the proportion of the structural units of the organopolysiloxane. For example, by increasing the value of M2 + D2 + T2 in the above formula [1], formula [2], or formula [3], that is, by increasing the content of polymerizable functional groups, the density of the obtained cured product can be increased and the refractive index can be increased. Conversely, by decreasing the value of M2 + D2 + T2, that is, by decreasing the content of polymerizable functional groups, the density of the obtained cured product can be decreased and the refractive index can be lowered. In addition, the refractive index of the cured product can be controlled by changing the component proportions of the organopolysiloxane-containing composition.

[0106] [Method for Manufacturing Optical Waveguide] The method for manufacturing the optical waveguide of the present invention is not particularly limited, and various methods can be used. Specifically, photolithography, replication (stamper) method, direct exposure method, reactive ion etching (RIE) method, methods based on injection molding, photobleaching method, direct writing method, self-forming method, etc. can be used. It is also possible to manufacture the optical waveguide by a method such as nanoimprinting.

[0107] An example of a method for manufacturing an optical waveguide will be described below with reference to FIG. 1 . First, an organopolysiloxane-containing composition for forming the undercladding portion 32 is applied onto a substrate. The organopolysiloxane-containing composition is then cured using external energy to form the undercladding portion 32. Next, an organopolysiloxane-containing composition for forming the core portion 20 is applied onto the undercladding portion 32. The organopolysiloxane-containing composition is then patterned using a photolithography process to form the core portion 20 on the undercladding portion 32. If the width of the core portion 20 is to vary along the light propagation direction, the core portion 20 can be formed by exposure using a photomask whose width varies along the light propagation direction, followed by development. After the core portion 20 is formed, post-baking may be performed as needed. The exposure atmosphere may be air or an inert atmosphere. Exposure in an inert atmosphere can reduce the amount of uncured layer that occurs on the surface of the polymer layer. As described above, post-baking may be performed as necessary. Post-baking may promote curing and improve adhesion between the polymer layer and the substrate, and adhesion between polymer layers themselves. Examples of post-baking conditions include a temperature of 50°C to 200°C for several tens of seconds to 60 minutes, or a temperature of 80°C to 150°C for several tens of seconds to 60 minutes.

[0108] Next, an organopolysiloxane-containing composition for forming the overclad 31 is applied onto the underclad 32 and the core 20. The organopolysiloxane-containing composition is then cured using external energy to form the overclad 31. The optical waveguide 10 can be manufactured by the above method. As mentioned above, the terms "underclad" and "overclad" are used in this specification merely for convenience. Here, the underclad refers to the material that covers the lower part of the core during manufacturing, and the overclad refers to the material that covers the upper left and right sides of the core. However, depending on the application, the underclad and overclad may be reversed, or the two may be integrated. After the core and clad of the optical waveguide are fabricated on the substrate, the optical waveguide may be peeled off from the substrate.

[0109] The substrate may be a silicon wafer, a silicon wafer with an oxide film, a polyimide resin, an epoxy resin, a PEEK resin, a liquid crystal polymer, glass, a glass epoxy substrate, or the like. The surface of the substrate to be used is preferably subjected to ozone treatment, plasma treatment, corona treatment, or the like in advance to remove any deposits on the surface, prevent the organopolysiloxane-containing composition to be applied from being repelled, and improve adhesion. Similarly, before forming the core and before forming the cladding, the surfaces on which the core and cladding will be formed are preferably subjected to ozone treatment, plasma treatment, corona treatment, or the like in advance.

[0110] In this first embodiment, the maximum length (H) in the thickness direction and the maximum length (L) in the width direction of the core portion of the optical waveguide core portion 20 in a cross section can be controlled, for example, by the method for manufacturing the optical waveguide. Specifically, when manufacturing by a photolithography process, the maximum length (H) in the thickness direction of the core portion can be controlled by adjusting the coating thickness when applying the organopolysiloxane-containing composition for forming the core portion 20. Then, by performing photolithography using a photomask on which a line with a line width close to the expected maximum length (H) in the thickness direction of the core portion is drawn, the ratio H / L can be controlled to a range of 0.4 to 3.

[0111] In this second embodiment, the taper angle of the optical waveguide core portion 20 can be controlled, for example, by the method for manufacturing the optical waveguide. Specifically, when manufacturing by a photolithography process, the taper angle can be controlled by adjusting the gap between the coating film of the organopolysiloxane-containing composition used to form the core portion 20 and the photomask. For example, the taper angle can be reduced by increasing the gap. The taper angle can also be controlled by adjusting the focus of the exposure machine.

[0112] The materials constituting the core portion and the clad portion are not particularly limited, but it is preferable that at least one of the core portion and the clad portion be composed of a cured product obtained by curing the above-mentioned organopolysiloxane-containing composition having a polymerizable functional group, it is more preferable that both be composed of a cured product obtained by curing an organopolysiloxane-containing composition, and it is even more preferable that the organopolysiloxane-containing composition be composed of a cured product obtained by curing an organopolysiloxane-containing composition having a polymerizable alkenyl group.

[0113] The undercladding portion 32 and the overcladding portion 31 may be made of the same material or different materials, but it is preferable to use an organopolysiloxane-containing composition having different refractive indices after curing. When materials having different refractive indices are used for the undercladding portion 32 and the overcladding portion 31, the state of light confinement in the optical waveguide 10 can be controlled.

[0114] [Optical Member] The optical waveguide of the present invention has reduced transmission loss and high patterning properties, allowing for easy drawing of thin lines of, for example, 10 μm or less. Therefore, it can be suitably used, for example, in single-mode optical waveguides. Furthermore, since the organopolysiloxane used as a raw material for the optical waveguide of the present invention exhibits high transparency in the near-infrared region, it can also be suitably used in near-infrared optical waveguides. Optical members having the optical waveguide of the present invention are also within the scope of the present invention. In addition to the optical waveguide or near-infrared optical waveguide described above, the optical member of the present invention may also include connecting members such as mirrors and connectors for connecting to optical fibers or silicon photonics optical circuits.

[0115] The present invention will be described in more detail by the following examples, but the present invention is not limited thereto.

[0116] [Method for evaluating organopolysiloxane] (1) １ H-NMR Measurement Method: Apparatus: AVANCE NEO 400, BBFO Probe (5 mm diameter), manufactured by Bruker Japan Co., Ltd. Measurement Conditions: Pulse repetition time / 5 seconds, Scan count / 16 times, Measurement mode / single pulse, Measurement temperature / 25°C, Flip angle / 30°, Spin / 20 Hz, Measurement temperature 25°C Sample Preparation: 60 mg of the organopolysiloxane to be measured was weighed out, and 12 mg of N,N-dimethylformamide was added as an internal standard. Further, deuterated chloroform was added to dissolve the sample to a total mass of 1 g, and the solution was placed in an NMR sample tube. Calculation of Functional Group Content: The functional group content was estimated from the ratio of the signal intensity of each component to the signal intensity of the internal standard N,N-dimethylformamide, and the weighed value.

[0117] (2) ２９ Si-NMR measurement method Sample preparation: Tris(2,4-pentanedionato)chromium(III) was added to deuterated chloroform to a concentration of 0.5 mass %. ２９ A solvent for Si-NMR measurement was obtained. 1.5 g of the organopolysiloxane to be measured was weighed out and ２９ 2.5 ml of a solvent for Si-NMR measurement was added to dissolve the solution, which was then placed in an NMR sample tube. (2)-1: Organopolysiloxanes A-1, A-2, and B-1 described below２９ Si-NMR Measurement Apparatus: JNM-ECS400 manufactured by JEOL Ltd., TUNABLE Probe (10 mm diameter): Si-free, AT10 probe Measurement conditions: Pulse repetition time / 16 seconds, Scan number / 1024 times, Measurement mode / non-gated decoupled pulse method (NNE), Flip angle / 90°, Spin / none, Measurement temperature / 25°C (2)-2: Organopolysiloxane B-2 described later ２９ Si-NMR Measurement Apparatus: AVANCE NEO 600, BBO Cryo Probe (5 mm diameter), manufactured by Bruker Japan Co., Ltd. Measurement conditions: Pulse repetition time / 16 seconds, number of scans / 1024 times, measurement mode / inverse gate decoupling measurement, flip angle / 90°, spin / none, measurement temperature / 25°C <Calculation of constitutional units> The signal intensity of each unit of silicon was measured, and the above １ The constituent ratio of silicon units was calculated from the ratio of the signal intensity measured by H-NMR and the ratio of the functional group content.

[0118] Organopolysiloxanes A-1 and A-2 used to form the core portion were prepared according to the following procedure.

[0119] Synthesis Example 1 Using 62.68 g of methyl silicate MS51 manufactured by Mitsubishi Chemical Corporation, 150.00 g of 3-methacryloyloxypropyltrimethoxysilane KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd., and 32.66 g of hexamethyldisiloxane manufactured by Nacalai Tesque, Inc., 122.67 g of toluene and 122.67 g of methanol as solvents, and a mixture of 72.98 g of 1N hydrochloric acid and 72.98 g of methanol as catalyst and water, hydrolysis and condensation were carried out while maintaining the temperature between 15° C. and 40° C. The reaction solution was then neutralized and washed with demineralized water, after which the solvent and water were removed and the mixture was filtered, yielding 34 g of the target liquid organopolysiloxane A-1.

[0120] Synthesis Example 2 Organopolysiloxane A-2 was obtained in the same manner as in Synthesis Example 1, except that 3-methacryloyloxypropyltrimethoxysilane KBM503 manufactured by Shin-Etsu Chemical Co., Ltd. and dimethoxydimethylsilane manufactured by Tokyo Chemical Industry Co., Ltd. were used.

[0121] Organopolysiloxanes B-1 and B-2 used to form the clad portion were prepared according to the following procedure.

[0122] Synthesis Example 3 Organopolysiloxane B-1 was obtained in the same manner as in Synthesis Example 1, except that 104.65 g of methyl silicate MS51 manufactured by Mitsubishi Chemical Corporation, 125.00 g of 3-methacryloyloxypropyltrimethoxysilane KBM-503 manufactured by Shin-Etsu Chemical Co., Ltd., and 21.64 g of hexamethyldisiloxane manufactured by Nacalai Tesque, Inc. were used.

[0123] Synthesis Example 4 Organopolysiloxane B-2 was obtained in the same manner as in Synthesis Example 1, except that 3-methacryloyloxypropyltrimethoxysilane KBM503 manufactured by Shin-Etsu Chemical Co., Ltd. and dimethoxydimethylsilane manufactured by Tokyo Chemical Industry Co., Ltd. were used.

[0124] The proportions of the constituent units of the organopolysiloxane obtained from NMR measurements are shown in Table 1.

[0125]

[0126] An organopolysiloxane-containing composition for use in forming an optical waveguide was prepared using the organopolysiloxane used to form the core portion according to the following procedure. 100 parts by weight of the organopolysiloxane used to form the core portion, 2 parts by weight of 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (Omnirad 369, manufactured by IGM Resins B.V.), 10 parts by weight of pentaerythritol tetrakis(3-mercaptobutyrate) (PE1, manufactured by Resonac Co., Ltd.), and 20 parts by weight of propylene glycol monomethyl ether acetate were placed in a container and stirred for 2 hours to obtain a composition for use in forming a polymer optical waveguide. The composition obtained using organopolysiloxane A-1 according to the above procedure was designated C-1, and the composition obtained using organopolysiloxane A-2 according to the above procedure without PE1 was designated C-2.

[0127] An organopolysiloxane-containing composition for use in forming an optical waveguide was prepared using the organopolysiloxane used to form the cladding portion according to the following procedure. 100 parts by mass of the organopolysiloxane used to form the cladding portion, 2 parts by mass of 2-benzyl-2-(dimethylamino)-4'-morpholinobutyrophenone (Omnirad 369, manufactured by IGM Resins B.V.), and 20 parts by mass of propylene glycol monomethyl ether acetate were placed in a container and stirred for 2 hours to obtain a composition for use in forming an optical waveguide. The composition obtained using organopolysiloxane B-1 according to the above procedure is designated D-1, and the composition obtained using organopolysiloxane B-2 according to the above procedure is designated D-2.

[0128] The refractive index at a wavelength of 1,300 nm of the cured films prepared from the organopolysiloxanes A-1, A-2, B-1, and B-2 was measured by the following procedure: Compositions C-1, C-2, D-1, and D-2 were applied to a glass substrate by spin coating, and the coating was irradiated with an LED having a wavelength of 365 nm at an integrated light intensity of 500 mJ / cm. ２ The refractive index of the resulting cured films was measured using a prism coupler (Metricon KPR-2000), and the refractive index at a wavelength of 1,300 nm of the cured films prepared from compositions C-1, C-2, D-1, and D-2 was 1.459, 1.466, 1.441, and 1.456, respectively.

[0129] The organopolysiloxane-containing composition used for forming the optical waveguide obtained by the above procedure was used to fabricate the following five optical waveguides by the following procedure.

[0130] Example 1 Composition D-1 was applied to an ozone-treated silicon wafer as a substrate so that the thickness after heat curing would be about 5 μm, and then the coating was dried to obtain a coated substrate. The resulting coating was then exposed to light without using a photomask (the intensity at a wavelength of 365 nm during exposure was 40 mW / cm). ２ , exposure dose 500 mJ / cm ２). Thereafter, insufficiently cured portions of the coating surface were removed using propylene glycol monomethyl ether acetate, followed by 2-propanol, and then the coating was dried. Through these operations, an undercladding portion was formed on the substrate. Next, Composition C-1 was applied onto the undercladding portion so that the thickness after heat curing would be approximately 5 to 7 μm. This was then subjected to a drying treatment to obtain a coated substrate. Next, the resulting coating was exposed to light using a photomask (having multiple exposed portions with a width of 3 to 10 μm and a length of 4 cm, spaced at a pitch of 125 μm) at a wavelength of 365 nm with an intensity of 500 mW / cm ２ , exposure dose 1000 mJ / cm ２ The coating was then exposed to light so that the thickness of the coating was about 10 μm. Thereafter, the unexposed portions of the coating were removed using propylene glycol monomethyl ether acetate, followed by 2-propanol, and then dried. These operations resulted in a substrate in which a core portion was formed on an underclad portion (underclad-attached core substrate). Next, Composition D-1 was applied onto the underclad-attached core substrate so that the thickness after heat curing would be about 10 μm. This was followed by a drying treatment to obtain a coated substrate. Next, the resulting coating was exposed to light without using a photomask (the intensity at a wavelength of 365 nm during exposure was 40 mW / cm ２ , exposure dose 500 mJ / cm ２ ). Then, using propylene glycol monomethyl ether acetate and then 2-propanol, insufficient cured portions of the coating surface were removed, and the coating was then dried. Finally, the coating was heated and cured at 150°C for 1 hour to obtain an optical waveguide sample X-1 having an underclad / core / overclad structure.

[0131] Example 2 An optical waveguide sample X-2 was obtained in the same manner as in Example 1, except that C-2 was used as the composition for forming the core portion and D-2 was used as the composition for forming the cladding portion.

[0132] Comparative Example 1 Composition C-1 was applied to a silicon wafer as a substrate so that the thickness after heat curing would be about 5 to 7 μm, and then the coating was dried. Next, the resulting coating film was subjected to a photolithography using the same photomask as in Example 1, with an intensity of 500 mW / cm at a wavelength of 365 nm.２ , exposure dose 1000 mJ / cm ２ Thereafter, the unexposed portions of the coating film were removed using propylene glycol monomethyl ether acetate and then 2-propanol, and then dried to obtain a substrate on which a core portion had been formed. Next, Composition D-1 was applied onto the substrate having the core portion so that the thickness after heat curing would be about 10 μm, and then dried to obtain a coated substrate. Next, the obtained coating film was exposed without using a photomask (the intensity at a wavelength of 365 nm during exposure was 40 mW / cm ２ , exposure dose 500 mJ / cm ２ ). Then, using propylene glycol monomethyl ether acetate and then 2-propanol, insufficient cured portions of the coating surface were removed, and the coating was then dried. Finally, the coating was heated and cured at 150°C for 1 hour to obtain optical waveguide sample Y-1, which does not have an undercladding portion as compared to Example 1.

[0133] Comparative Example 2 Composition D-1 was applied to a silicon wafer as a substrate so that the thickness after heat curing would be about 5 μm, and then a drying treatment was carried out to obtain a coated substrate. Next, the obtained coating film was exposed to light without using a photomask (the intensity at the exposure wavelength of 365 nm was 40 mW / cm ２ , exposure dose 500 mJ / cm ２ ). Thereafter, using propylene glycol monomethyl ether acetate, and then using 2-propanol, insufficiently cured portions of the coating surface were removed, and the coating was then dried. Through these operations, an undercladding portion was formed on the substrate. Next, Composition C-1 was applied onto the undercladding portion so that the thickness after heat curing would be approximately 3 to 4 μm. After that, a drying treatment was performed, and a coated substrate was obtained. Next, using the same photomask as in Example 1, the obtained coating film was subjected to a photolithography at a wavelength of 365 nm with an intensity of 500 mW / cm. ２ , exposure dose 1000 mJ / cm ２The coating was then exposed to light so that the thickness of the coating was about 10 μm. Thereafter, the unexposed portions of the coating were removed using propylene glycol monomethyl ether acetate, followed by 2-propanol, and then dried. These operations resulted in a substrate in which a core portion was formed on an underclad portion (underclad-attached core substrate). Next, Composition D-1 was applied onto the underclad-attached core substrate so that the thickness after heat curing would be about 10 μm. This was followed by a drying treatment to obtain a coated substrate. Next, the resulting coating was exposed to light without using a photomask (the intensity at a wavelength of 365 nm during exposure was 40 mW / cm ２ , exposure dose 500 mJ / cm ２ ). Then, using propylene glycol monomethyl ether acetate and then 2-propanol, insufficient cured portions of the coating surface were removed, and the coating was then dried. Finally, the coating was heated and cured at 150°C for 1 hour to obtain optical waveguide sample Y-2 having an underclad / core / overclad structure.

[0134] Comparative Example 3 Composition D-1 was applied to a silicon wafer as a substrate so that the thickness after heat curing would be about 5 μm, and then a drying treatment was carried out to obtain a coated substrate. Next, the obtained coating film was exposed to light without using a photomask (the intensity at the exposure wavelength of 365 nm was 40 mW / cm ２ , exposure dose 500 mJ / cm ２ ). Thereafter, insufficiently cured portions of the coating surface were removed using propylene glycol monomethyl ether acetate, followed by 2-propanol, and then the coating was dried. Through these operations, an undercladding portion was formed on the substrate. Next, Composition C-1 was applied so that the thickness would be approximately 5 to 7 μm after heat curing. A drying treatment was performed to obtain a coated substrate. Next, the obtained coating was subjected to a photolithography test using the same photomask as in Example 1, with the gap between the photomask and the coating being larger than in Examples 1 and 2 and Comparative Example 1, at a wavelength of 365 nm with an intensity of 500 mW / cm. ２ , exposure dose 1000 mJ / cm ２Thereafter, the unexposed portions of the coating film were removed using propylene glycol monomethyl ether acetate, followed by 2-propanol, and then dried. Next, Composition D-1 was applied onto the underclad-attached core substrate so that the thickness after heat curing would be about 10 μm, and then a drying treatment was carried out to obtain a coated substrate. Next, the resulting coating film was exposed without using a photomask (the intensity at a wavelength of 365 nm during exposure was 40 mW / cm ２ , exposure dose 500 mJ / cm ２ ). Then, using propylene glycol monomethyl ether acetate and then 2-propanol, insufficiently cured portions of the coating surface were removed, and the coating was then dried. Finally, the coating was heated and cured at 150°C for 1 hour to obtain optical waveguide sample Y-3, which had an underclad / core / overclad structure and a smaller taper angle compared to Example 1.

[0135] The H / L ratios of the core portions of the optical waveguide samples X-1, X-2, and Y-1 and Y-2 obtained by the above procedure were measured using the following procedure. The end of the optical waveguide was cut, and the cross section of the obtained sample piece was observed using an SEM (SU1510, manufactured by Hitachi High-Technologies Corporation). H / L was calculated by taking the maximum length in the width direction of the cross section of the core portion as L [μm] and the maximum length in the thickness direction as H [μm]. The H / L ratios of the core portions of the optical waveguide samples X-1 and Y-1 were 0.48. The H / L ratios of the core portion of the optical waveguide sample X-2 were 0.69. The H / L ratios of the core portion of the optical waveguide sample Y-2 were 0.38.

[0136] The taper angles of the core portions of optical waveguide samples X-1, X-2, Y-1, and Y-3 obtained by the above procedure were measured by the following procedure. The ends of the optical waveguides were cut, and the cross sections of the obtained sample pieces were observed using an SEM (SU1510, manufactured by Hitachi High-Technologies Corporation). The taper angles of the core portions of optical waveguide samples X-1 and Y-1 were 83°. The taper angle of the core portion of optical waveguide sample X-2 was 83°. The taper angle of the core portion of optical waveguide sample Y-3 was 47°.

[0137] The transmission loss of the optical waveguide samples X-1, X-2, and Y-1 obtained by the above procedure, and the connection loss of the optical waveguide samples X-1 and X-2 were measured by the following procedure.

[0138] Both ends of the optical waveguide were cut to prepare samples of several optical path lengths, and single-mode fibers were spliced ​​to both ends. A temperature-controlled fiber-output high-power LD stabilized light source (LDS1005) manufactured by Precise Gauge was connected to the input single-mode fiber, and a power meter (MT9810B) manufactured by Anritsu was connected to the output single-mode fiber, and the insertion loss of each sample was measured. When the transmission loss was calculated from the change in insertion loss with respect to the optical path length, the transmission losses of optical waveguide samples X-1 and X-2 were 0.31 dB / cm and 0.30 dB / cm, respectively. On the other hand, the transmission loss of optical waveguide sample Y-1 was 1.5 dB / cm. In addition, the connection loss was calculated from the intercept of the approximation line of a graph with the horizontal axis representing the waveguide length and the vertical axis representing the insertion loss. The connection losses of optical waveguides X-1 and X-2 were 2.00 dB and 1.20 dB, respectively.

[0139] The polarization-dependent loss of optical waveguide samples X-1, X-2, Y-2, and Y-3 obtained by the above procedure was measured using the following procedure. Both ends of the optical waveguide were cut to prepare samples with an optical path length of approximately 3 cm, and single-mode fibers were connected to both ends. A temperature-controlled fiber-output high-power LD stabilized light source (LDS1005) manufactured by Precise Gauge was connected to the input single-mode fiber, and a power meter (MT9810B) manufactured by Anritsu was connected to the output single-mode fiber. A Thorlabs polarization controller (FPC561) was used to change the polarization state of light incident on the sample, and the polarization-dependent loss was measured. The polarization-dependent losses of optical waveguide samples X-1, X-2, Y-2, and Y-3 were 0.2 dB, 0.3 dB, 0.6 dB, and 0.6 dB, respectively.

[0140]

[0141] [Discussion of Results] Optical waveguide samples X-1 and X-2, which have an undercladding portion, have significantly reduced transmission loss compared to optical waveguide sample Y-1, which does not have an undercladding portion. This result demonstrates that providing an undercladding portion efficiently confines light propagating within the core within the core, achieving high optical propagation performance. Furthermore, a comparison of optical waveguide samples X-1 and X-2, in which the H / L ratio in the cross-sectional shape of the core is 0.4 or more, with optical waveguide sample Y-2, in which the H / L ratio is less than 0.4, and a comparison of X-1 and X-2, in which the taper angle in the cross-sectional shape of the core is 50° or more and 130° or less, with Y-3, in which the taper angle is less than 50°, suggests that the near field pattern on the core output side approaches a perfect circle, thereby reducing polarization-dependent loss in optical propagation within the core.

[0142] The optical waveguide of the present invention exhibits both low transmission loss and low polarization dependent loss, and exhibits good optical propagation characteristics. Due to these characteristics, the optical waveguide of the present invention can be used as an optical component for optical interconnection and other applications.

[0143] 10 Optical waveguide 20 Core portion 30 Cladding portion 31 Overcladding portion 32 Undercladding portion 40 Taper angle

Claims

1. An optical waveguide comprising a core portion that propagates light and a cladding portion having a refractive index lower than that of the core portion, the cladding portion having an undercladding portion in contact with a part of the core portion, and in a cross-sectional shape of the core portion in a direction perpendicular to the light propagation direction, the direction of the line where the core portion and the undercladding portion contact each other is the width direction, and the direction perpendicular to the width direction is the thickness direction, and the maximum length in the width direction of the cross section of the core portion is L [μm] and the maximum length in the thickness direction is H [μm], H / L is 0.4 to 3, and at least one of the core portion and the cladding portion is composed of a cured product obtained by curing an organopolysiloxane-containing composition having a polymerizable functional group represented by the following formula [1]. (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (SiO ４／２ ) Ｑ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[1] [In formula [1], R １ ~R ５ , R ７ ~R １１ R is independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of organic groups are present, they may be the same or different from each other, 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0≦Q, 0<M2+D2+T2, 0<D1+D2+T1+T2+Q, M1+M2+D1+D2+T1+T2+Q=1.] 2. An optical waveguide comprising a core portion that propagates light and a cladding portion having a refractive index lower than that of the core portion, the cladding portion having an undercladding portion in contact with a part of the core portion, in a cross-sectional shape of the core portion in a direction perpendicular to the light propagation direction, the direction of the line where the core portion and the undercladding portion are in contact is the width direction, and the direction perpendicular to the width direction is the thickness direction, and the taper angle of the core portion is the angle between the tangent line of the core side portion corresponding to 1 / 2 the maximum length of the core portion in the thickness direction and the undercladding, the taper angle is 50° or more and 130° or less, and at least one of the core portion and the cladding portion is composed of a cured product obtained by curing an organopolysiloxane-containing composition having a polymerizable functional group represented by the following formula [1]. (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (SiO ４／２ ) Ｑ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[1] [In formula [1], R １ ~R ５ , R ７ ~R １１ R is independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of organic groups are present, they may be the same or different from each other, 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0≦Q, 0<M2+D2+T2, 0<D1+D2+T1+T2+Q, M1+M2+D1+D2+T1+T2+Q=1.] 3. The optical waveguide according to claim 1 or 2, wherein the difference in refractive index between said core portion and said cladding portion is 0.005 or more and 0.05 or less.

4. The optical waveguide according to claim 1 or 2, wherein in a cross section of said core portion perpendicular to the light propagation direction, the length of said undercladding portion in the thickness direction is 1 μm or more.

5. The optical waveguide according to claim 1 or 2, wherein said cladding portion has an overcladding portion present in a portion of said core portion not in contact with said undercladding portion.

6. The optical waveguide according to claim 1 or 2, wherein the refractive index of said core portion at a wavelength of 1,300 nm is 1.400 or more and 1.520 or less.

7. The optical waveguide according to claim 1 or 2, wherein the organopolysiloxane having a polymerizable functional group is represented by the following formula [2]. (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (SiO ４／２ ) Ｑ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[2] [In formula [2], R １ ~R ５ , R ７ ~R １１ R is independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of organic groups are present, they may be the same or different from each other, 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0<Q, 0<M2+D2+T2 M1+M2+D1+D2+T1+T2+Q=1.] 8. The optical waveguide according to claim 1 or 2, wherein the organopolysiloxane having a polymerizable functional group is represented by the following formula [3]. (R １ R ２ R ３ SiO １／２ ) Ｍ１ (R ４ R ５ R ６ SiO １／２ ) Ｍ２ (R ７ R ８ SiO ２／２ ) Ｄ１ (R ９ R ６ SiO ２／２ ) Ｄ２ (R １０ SiO ３／２ ) Ｔ１ (R ６ SiO ３／２ ) Ｔ２ (O １／２ R １１ ) Ｙ１ (O １／２ R ６ ) Ｙ２ ...[3] [In formula [3], R １ ~R ５ , R ７ ~R １１ R is independently one or more groups selected from the group consisting of organic groups and hydrogen atoms. １ ~R ３ , R ７ , R ８ , R １０ and R １１ does not contain a polymerizable functional group. ６ represents one or more organic groups containing a polymerizable functional group, and when a plurality of organic groups are present, they may be the same or different from each other, 0≦M1, 0≦D1, 0≦T1, 0≦Y1, 0≦Y2, 0<M2+D2+T2, 0<D1+D2+T1+T2, M1+M2+D1+D2+T1+T2=1.] 9. The optical waveguide according to claim 1 or 2, wherein in the formula [1], 0.02≦Y1≦0.

25.

10. The optical waveguide according to claim 1 or 2, wherein in the formula [1], 0<M2+D2+T2≦0.

25.

11. The optical waveguide according to claim 1 or 2, wherein in the formula [1], 0.12<M2+D2+T2≦0.

25.

12. The optical waveguide according to claim 7, wherein in the formula [2], 0.02≦Y1≦0.

25.

13. The optical waveguide according to claim 7, wherein in the formula [2], Q satisfies 0.04≦Q.

14. The optical waveguide according to claim 8, wherein in the formula [3], 0<D1+D2.

15. The optical waveguide according to claim 8, wherein in the formula [3], 0.1<D1+D2.

16. The optical waveguide according to claim 8, wherein in the formula [3], 0<D1.

17. The optical waveguide according to claim 8, wherein in the formula [3], 0.02≦Y1≦0.

25.

18. The optical waveguide according to claim 8, wherein in the formula [3], 0<T1+T2.

19. The optical waveguide according to claim 8, wherein in the formula [3], 0<D1+D2 and 0<T1+T2.

20. The above R ６ The optical waveguide of claim 1 or 2, wherein comprises a polymerizable alkenyl group.

21. The above R ６ The optical waveguide according to claim 1 or 2, wherein contains an acryloyl group and / or a methacryloyl group.

22. The optical waveguide according to claim 1 or 2, wherein the organopolysiloxane having a polymerizable functional group does not contain an aromatic structure.

23. The above R ６ 3. The optical waveguide according to claim 1, wherein is an acryloyloxypropyl group and / or a methacryloyloxypropyl group.

24. The optical waveguide according to claim 1 or 2, which is for single mode.

25. An optical member having the optical waveguide according to claim 1 or 2.

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