Patent Application
20240369782
The present invention relates to an optical member and an optical device.
As an invention related to a conventional optical member, for example, a semiconductor optical coupling device described in Patent Document 1 has been known. The semiconductor optical coupling device includes a laser diode, an optical isolator, and an optical fiber. The laser diode emits light. Light emitted from the laser diode passes through the optical isolator and enters the end surface of the optical fiber. The optical isolator prevents light reflected by the end surface of the optical fiber or the like from entering the laser diode.
By the way, in the semiconductor optical coupling device described in Patent Document 1, it is desired to reduce the size of the semiconductor optical coupling device and the cost of the semiconductor optical coupling device.
Therefore, an object of the present invention is to provide an optical member and an optical device capable of reducing the size of the optical member and the cost of the optical member.
An optical member according to an embodiment of the present invention includes: a first optical element including a first medium, and a first plurality of fillers in the medium and having a non-spherical shape that changes a traveling direction of light passing through the first medium; and a holding portion configured to hold an optical fiber such that the light emitted from the first optical element enters an end surface of the optical fiber.
According to the present invention, it can be achieved to reduce the size of the optical member and the cost of the optical member.
Hereinafter, an optical device 1 including an optical member 10 according to an embodiment of the present invention will be described with reference to the drawings.
In the present specification, directions are defined as follows. As illustrated in
The optical device 1 is a transmission device of an optical communication system. As illustrated in
The optical member 10 has a function of forming an optical path, a function of concentrating light, and a function of changing a traveling direction of light. More specifically, as illustrated in
As illustrated in
The medium M2 of the prism 12 is glass. Glass is a material that is amorphous and exhibits a glass transition phenomenon. Examples of the glass include glass of simple oxides such as SiO2, B2O3, P2O5, GeO2, and As2O3, glass of silicates such as Li2O—SiO2, Na2O—SiO2, and K2O—SiO2, glass of aluminosilicates such as Na2O—Al2O3—SiO2 and CaO—Al2O3—SiO2, glass of borates such as LiO2—Ba2—O3 and Na2O—B2O3, glass of aluminoborates such as CaO—Al2O3—B2O3, and glass of borosilicates such as Na2O—Al2O3—B2O3—SiO2.
The plurality of fillers P2 are metal oxide particles such as crystalline silica, amorphous silica, alumina, magnesium oxide, and titanium oxide. The refractive index of the plurality of fillers is a value between the upper limit value n1 and the lower limit value n2 of the refractive index of the medium M2 of the prism 12 (second optical element). However, in order to suppress reflection due to a difference in refractive index at the interface, it is preferable that the refractive index of the plurality of fillers P2 is close to the refractive index of the medium M2. In addition, it is preferable that the higher the amorphous property of the plurality of fillers P2 is, the higher the permeability of the plurality of fillers P2 is.
The plurality of fillers P2 have a non-spherical shape. The non-spherical shape is a shape that is not a sphere. The shape that is not a sphere is a shape in which the distance from the center to the outer edge is not constant, and is, for example, a rectangular parallelepiped shape or an elliptical spherical shape. The non-spherical shape may be a shape in which a large number of irregularities are provided on the surface of a sphere. In the present embodiment, the plurality of fillers P2 have an elliptical spherical shape. The plurality of fillers P2 have a longitudinal direction and a short direction. The longitudinal direction is a length direction of the longest portion of the plurality of fillers P2. The short direction is a length direction of the shortest portion of the plurality of fillers P2 in the direction orthogonal to the longitudinal direction. The longitudinal direction of the plurality of fillers P2 has a length of L1. The short direction of the plurality of fillers P2 has a length of L2. The light has a wavelength of λ. At this time, L2/L1>L1/λ is satisfied. L1 and L2 are average values of 20 fillers within the plurality of fillers P2 included in the prism 12.
The plurality of fillers P2 are uniformly dispersed throughout the prism 12. Thus, the plurality of fillers P2 are provided on a path of light. In particular, the plurality of fillers P2 are provided at the incident surface S1.
As illustrated in
The gradient index lens 14a has a cylindrical shape having a center axis extending in the front-rear direction. As illustrated in
As illustrated in
The medium M1 of the gradient index lens 14a is glass. Glass is a material that is amorphous and exhibits a glass transition phenomenon. Examples of the glass include glass of simple oxides such as SiO2, B2O3, P2O5, GeO2, and As2O3, glass of silicates such as Li2O—SiO2, Na2O—SiO2, and K2O—SiO2, glass of aluminosilicates such as Na2O—Al2O3—SiO2 and CaO—Al2O3—SiO2, glass of borates such as LiO2—Ba2—O3 and Na2O—B2O3, glass of aluminoborates such as CaO—Al2O3—B2O3, and glass of borosilicates such as Na2O—Al2O3—B2O3—SiO2.
Examples of a method for providing the gradient index lens 14a with a refractive index distribution include a method described below. By impregnating a cylindrical glass with a molten salt, ions in the glass are replaced with ions in the molten salt, and metal ions are permeated into the cylindrical glass.
The plurality of fillers P1 are metal oxide particles such as crystalline silica, amorphous silica, alumina, magnesium oxide, and titanium oxide. The refractive index of the plurality of fillers P1 is a value between the upper limit value n1 and the lower limit value n2 of the refractive index of the medium M1 of the gradient index lens 14a (first optical element). However, in order to suppress reflection due to a difference in refractive index at the interface, it is preferable that the refractive index of the plurality of fillers P1 is close to the refractive index of the medium M1. In addition, it is preferable that the higher the amorphous property of the plurality of fillers P1 is, the higher the permeability of the plurality of fillers P1 is.
The plurality of fillers P1 have a non-spherical shape. Specifically, the plurality of fillers P1 have an elliptical spherical shape. The plurality of fillers P1 have a longitudinal direction and a short direction. The longitudinal direction is a length direction of the longest portion of the plurality of fillers P1. The short direction is a length direction of the shortest portion of the plurality of fillers P1 in the direction orthogonal to the longitudinal direction. The longitudinal direction of the plurality of fillers P1 has a length of L1. The short direction of the plurality of fillers P1 has a length of L2. The light has a wavelength of λ. At this time, L2/L1>L1/λ is satisfied. L1 and L2 are average values of 20 fillers within the plurality of fillers P1 included in the gradient index lens 14a.
The plurality of fillers P1 are uniformly dispersed throughout the gradient index lenses 14a to 14e. Thus, the plurality of fillers P1 are provided on a path of light. In particular, the plurality of fillers P1 are provided at the incident surface S4.
The supporting portion 14f supports the gradient index lenses 14a to 14e. Specifically, the supporting portion 14f has an elliptical spherical shape. The gradient index lenses 14a to 14e are embedded in the supporting portion 14f. However, each of the incident surfaces S4 of the gradient index lenses 14a to 14e is exposed from the surface of the supporting portion 14f on the negative side of the X-axis. Each of the emission surfaces S5 of the gradient index lenses 14a to 14e is exposed from the surface of the supporting portion 14f on the positive side of the X-axis. The material of the supporting portion 14f is the same glass as the medium M1 of the gradient index lens 14a.
The gradient index lenses 14a to 14e as described above are located on the positive side of the X-axis with respect to the prism 12. As a result, the incident surface S4 of the gradient index lenses 14a to 14e overlaps the emission surface S3 of the prism 12 as viewed in the X-axis direction.
As illustrated in
The frame 18 supports the prism 12, the lens portion 14, and the holding portion 16. More specifically, the frame 18 includes supporting portions 18a and 18b and a join portion 18c. Each of the supporting portions 18a and 18b is a plate having two main surfaces arranged in the Y-axis direction. The supporting portions 18a and 18b are arranged in this order in the negative direction of the Y-axis. The end of the holding portion 16 on the positive side of the Y-axis and the end of the lens portion 14 on the positive side of the Y-axis are in contact with the supporting portion 18a. The end of the holding portion 16 on the negative side of the Y-axis and the end of the lens portion 14 on the negative side of the Y-axis are in contact with the supporting portion 18b. The surface of the holding portion 16 located on the negative side of the X-axis is in contact with the end of the supporting portion 18a on the positive side of the X-axis direction and the end of the supporting portion 18b on the positive side of the X-axis direction.
The join portion 18c is a plate having two main surfaces arranged in the X-axis direction. The end of the join portion 18c on the positive side of the Y-axis is in contact with the supporting portion 18a. The end of the join portion 18c on the negative side of the Y-axis is in contact with the supporting portion 18b. The material of the holding portion 16 is the same glass as the medium M2 of the prism 12 and the medium M1 of the gradient index lens 14a.
The lens portion 14 (first optical element), the prism 12 (second optical element), the holding portion 16, and the frame 18 as described above are integrally molded. That is, the lens portion 14 (first optical element), the prism 12 (second optical element), the holding portion 16, and the frame 18 can not be separated without being damaged.
As illustrated in
The light emitting elements 120a to 120e emit light in the positive direction of the Z-axis. The light emitting elements 120a to 120e are, for example, vertical cavity surface emitting lasers (VCSEL). The wavelength of the light is, for example, 1310 nm. The light emitting elements 120a to 120e are mounted on the positive main surface S11 of the circuit board 110. The light emitting elements 120a to 120e overlap the incident surface S1 of the prism 12 as viewed in the Z-axis direction.
In the optical device 1 as described above, the light emitting elements 120a to 120e emit light in the positive direction of the Z-axis. At this time, as illustrated in
Then, the light emitted from the prism 12 (second optical element) enters the gradient index lenses 14a to 14e (first optical element) via the incident surface S4. The light is concentrated when passing through the gradient index lenses 14a to 14e. Then, the light is emitted from the gradient index lenses 14a to 14e via the emission surface S5. Thereafter, the light enters the optical fibers 100a to 100e.
According to the optical member 10, it can be achieved to reduce the size of the optical member 10 and the cost of the optical member 10. Hereinafter, an optical device 1001 according to a comparative example will be described as an example.
As illustrated in
However, since the semiconductor optical coupling device described in Patent Document 1 requires an optical isolator, there are problems of an increased size of the semiconductor optical coupling device and higher cost of the semiconductor optical coupling device.
Therefore, in the optical device 1, the gradient index lenses 14a to 14e include the plurality of fillers P1. The prism 12 includes the plurality of fillers P2. As a result, a part of light is reflected by the plurality of fillers P1 while traveling in the medium M1. Similarly, a part of light is reflected by the plurality of fillers P2 while traveling in the medium M2. Note that the plurality of fillers P1 and P2 have a non-spherical shape. Therefore, the light reflected by the plurality of fillers P1 does not travel in the negative direction of the X-axis as illustrated in
As described above, in the optical member 10, by providing the plurality of fillers P1 and P2 without adding a new element, the reflected light is prevented from entering the light emitting elements 120a to 120e. Therefore, it can be achieved to reduce the size of the optical member 10 and the cost of the optical member 10.
In the optical member 10, the plurality of fillers P1 and P2 are provided on a path of light. As a result, light is easily reflected by the plurality of fillers P1 and P2.
In particular, in the optical member 10, the plurality of fillers P1 and P2 are provided at the incident surface S1 and S4. As a result, the light reflected on the incident surface S1 is reflected by the plurality of fillers P2 in a direction other than the negative direction of the Z-axis. Similarly, the light reflected on the incident surface S4 is reflected by the plurality of fillers P1 in a direction other than the negative direction of the X-axis. As a result, the light reflected by the plurality of fillers P1 and P2 is less likely to enter the light emitting elements 120a to 120e.
In the optical member 10, the refractive index of the plurality of fillers P1 is a value between the upper limit value n1 and the lower limit value n2 of the refractive index of the medium M1 of the gradient index lenses 14a to 14e. As a result, it is possible to reduce the influence of the plurality of fillers P1 on the optical characteristics of the gradient index lenses 14a to 14e.
In the optical member 10, when the longitudinal direction of the plurality of fillers P1 and P2 has a length of L1, the short direction of the plurality of fillers P1 and P2 has a length of L2, and the light has a wavelength of λ, L2/L1>L1/λ is satisfied. When A is larger than L1, Rayleigh scattering occurs. A spherical filler has more backscattering components in Rayleigh scattering, which is prevented in a non-spherical filler.
In the optical member 10, the prism 12 and the gradient index lenses 14a to 14e are integrally molded. This suppresses variations in the positional relationship between the prism 12 and the gradient index lenses 14a to 14e.
Hereinafter, an optical device 1a including an optical member 10a according to the first modification will be described with reference to the drawings.
The optical member 10a is different from the optical member 10 in that the prism 12 is not provided. In this case, each of the light emitting elements 120a to 120e is located on the negative side of the X-axis with respect to the gradient index lenses 14a to 14e. Then, light emitted from each of the light emitting elements 120a to 120e enters the gradient index lenses 14a to 14e (first optical element). Other structures of the optical member 10a are the same as those of the optical member 10, and thus description thereof is omitted. With the optical member 10a, it is possible to provide the same action and effect as those of the optical member 10.
Hereinafter, an optical device 1b including an optical member 10b according to the second modification will be described with reference to the drawings.
The optical member 10b is different from the optical member 10a in that the gradient index lens 140 (first optical element) and the gradient index lens 142 are provided instead of the gradient index lenses 14a to 14e (first optical element). The refractive index of the gradient index lens 140 decreases with distance from the center of the Z-axis direction to the positive direction or negative direction of the Z-axis direction. As a result, the gradient index lens 140 concentrates light so that the diameter of light traveling in the positive direction of the X-axis decreases in the Z-axis direction. The gradient index lens 140 includes a medium and a plurality of fillers.
The refractive index of the gradient index lens 142 decreases with distance from the center of the Y-axis direction to the positive direction or negative direction of the Y-axis direction. As a result, the gradient index lens 142 concentrates light so that the diameter of light traveling in the positive direction of the X-axis decreases in the Y-axis direction. The gradient index lens 142 includes a medium and a plurality of fillers.
Other structures of the optical member 10b are the same as those of the optical member 10a, and thus description thereof is omitted. With the optical member 10b, it is possible to provide the same action and effect as those of the optical member 10a.
Hereinafter, an optical device 1c including an optical member 10c according to the third modification will be described with reference to the drawings.
The optical member 10c is different from the optical member 10 in a position where the plurality of fillers P1 is provided. More specifically, the gradient index lenses 14a to 14e have concentration points. The concentration point is a position where light has a smallest diameter in the gradient index lenses 14a to 14e (first optical element). The plurality of fillers P1 are located at the concentration point. Thus, light is effectively scattered by the plurality of fillers P1. Other structures of the optical member 10c are the same as those of the optical member 10, and thus description thereof is omitted. With the optical member 10c, it is possible to provide the same action and effect as those of the optical member 10.
The optical member according to the present invention is not limited to the optical members 10 and 10a to 10c, and can be modified within the scope of the gist thereof. In addition, the structures of the optical members 10 and 10a to 10c may be arbitrarily combined.
Note that the first optical element and the second optical element may be optical elements other than a prism and a gradient index lens.
The plurality of fillers may be provided at positions other than the concentration point. The plurality of fillers does not have to be provided at the concentration point.
The plurality of fillers does not have to be provided at the incident surface.
At this time, L2/L1>L1/λ does not have to be satisfied.
Note that the optical device may include a reception device in addition to the transmission device. That is, the optical device may include a light receiving element in addition to the light emitting element. In this case, the first optical element and the second optical element corresponding to the light emitting element may contain a medium and a plurality of fillers.
Note that the position of the gradient index lens 140 and the position of the gradient index lens 142 may be interchanged.
It is possible that the optical member does not include a gradient index lens but includes a prism. In this case, the prism is the first optical element.
Note that the refractive index of the gradient index lens may change stepwise.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-042718 | Mar 2022 | JP | national |
The present application is a continuation of International application No. PCT/JP2022/040455, filed Oct. 28, 2022, which claims priority to Japanese Patent Application No. 2022-042718, filed Mar. 17, 2022, the entire contents of each of which are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2022/040455 | Oct 2022 | WO |
| Child | 18775101 | US |
