Photosynthesis device

Abstract

An optical multiplexing device capable of multiplexing a plurality of light beams, capable of reducing the diffusion angle of the emitted light compared to conventional devices, and capable of improving the light utilization efficiency. The optical multiplexing device has a plurality of entrances through which the plurality of light beams are respectively incident, a single exit port through which the light resulting from the multiplexing of the plurality of light beams is emitted, a first intersection region where one of the light beams incident from the entrances intersects with the other of the light beams, a reflecting surface that reflects the one of the light beams that has passed through the first intersection region, and a second intersection region where the one of the light beams reflected by the reflecting surface intersects again with the other of the light beams.

Description

[Technical field]

[0001] The present invention relates to an optical multiplexing device. [Background technology]

[0002] Conventionally, projector devices and display devices using light sources such as laser light-emitting elements are known. For example, a projector device is known that uses a condenser lens to condense light emitted from a light source such as a PLC (planar light circuit) onto a screen to generate a minute spot of light. In this device, an MEMS mirror arranged between the condenser lens and the screen is vibrated within a predetermined angle to scan the spot of light on the screen, forming an image. This type of MEMS mirror is used not only for MEMS scanning type projectors, but also for other types of projectors such as LCOS, DMD, and vector scan types. Furthermore, this type of projector is used not only for projectors, but also for a wide range of applications such as light sources for confocal microscopes, sensing, and illumination.

[0003] 2. Description of the Related Art Optical multiplexing devices have been proposed as devices capable of multiplexing a plurality of light beams and using them as a light source (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2020-154335 A [Patent Document 2] Japanese Patent Application Publication No. 10-142434 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the spread (diffusion angle) of the light emitted from the light source is large, vignetting occurs at the condenser lens and mirror, resulting in a problem of reduced light utilization efficiency. Also, when the area size of the light emitted from the light source is relatively large, the diameter of the spot light generated on the screen by the condenser lens becomes large, resulting in a problem of not being able to obtain a high-definition image.

[0006] The technology disclosed in Patent Document 1 involves connecting multiple optical waveguides extending in one direction at a specified angle and combining the incoming light beams, but this method results in the formation of an acute-angled portion in the combining region. In practice, it is impossible to process such an acute angle, so a flat portion of about 3 μm is required between the optical waveguides. This poses the problem that it is theoretically difficult to make the combining angle of the light beams smaller than a specified angle.

[0007] The technology disclosed in Patent Document 2 relates to an optical multiplexing element that multiplexes a first light from a first input optical waveguide and a second light from a second input optical waveguide that is substantially perpendicular to the first input optical waveguide by making the first light enter an output optical waveguide through a reflecting surface. In such a method, the optical axis of the multiplexed light beam must be set between the optical axis of the first light beam and the optical axis of the second light beam. Therefore, as the number of light beams to be multiplexed increases, the area size of the exit port increases. Therefore, there is a problem that the focused spot becomes large depending on the magnification of the lens that focuses the output light, and the light utilization efficiency decreases.

[0008] The present invention has been made in consideration of the above, and aims to provide an optical multiplexing device that can reduce the diffusion angle of the emitted light and the size of the exit port compared to conventional devices, thereby improving the light utilization efficiency. [Means for solving the problem]

[0009] (1) The present invention relates to an optical multiplexing device capable of multiplexing a plurality of light beams, the optical multiplexing device having a plurality of input ports through which the plurality of light beams are respectively incident, and a single output port through which light resulting from the multiplexing of the plurality of light beams exits, the optical multiplexing device having a first intersection region where one light beam incident from the input ports intersects with the other light beam, a reflecting surface where the one light beam that has passed through the first intersection region is reflected, and a second intersection region where the one light beam reflected by the reflecting surface again intersects with the other light beam.

[0010] (2) An optical multiplexing device as described in (1), comprising a multiplexing path in which the multiplexing beams are multiplexed, the rear end of the multiplexing path being connected to another multiplexing path in a subsequent stage or being provided with the exit port, the inclination angle of the reflecting surface with respect to the beam entering from the entrance port being set so that the second intersection region is the connection point with the other multiplexing path or the position of the exit port, and the multiplexing angle, which is the angle between the one beam reflected by the reflecting surface and the other beam, is 0.23° or less.

[0011] (3) An optical multiplexing device according to (1) or (2), comprising a waveguide having the incident port and a multiplexing path connected to the waveguide at a predetermined angle, the length of the waveguide being 1.5 mm or less.

[0012] (4) An optical multiplexing device according to any one of (1) to (3), comprising: a first optical path unit having the entrance, a second optical path unit having the entrance, the first intersection area, the reflecting surface, and the second intersection area; and a third optical path unit having the entrance, the first intersection area, the reflecting surface, the second intersection area, and the exit, wherein one or more of the second optical path units are provided as necessary. Effect of the Invention

[0013] According to the present invention, it is possible to provide an optical multiplexing device that can reduce the divergence angle of emitted light compared to the conventional device and improve the light utilization efficiency. [Brief description of the drawings]

[0014] [Figure 1] 1 is a schematic diagram illustrating a configuration of an optical multiplexing device according to a first embodiment. [Diagram 2] FIG. 2 is an enlarged view of a main part of FIG. [Diagram 3] 3 is a schematic diagram showing a configuration for making light enter an entrance according to the first embodiment. FIG. [Figure 4] 1 is a schematic diagram showing a configuration of an optical multiplexing device according to a first comparative example. [Diagram 5] FIG. 4 is a diagram showing a simulation result of the optical multiplexing device according to the first embodiment. [Figure 6] FIG. 11 is a diagram showing a simulation result of the optical multiplexing device according to the first comparative example. [Figure 7] FIG. 11 is a diagram showing a simulation result of the optical multiplexing device according to the second embodiment. [Figure 8] FIG. 11 is a diagram showing a simulation result of the optical multiplexing device according to the third embodiment. [Figure 9] FIG. 13 is a diagram showing a simulation result of the optical multiplexing device according to the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] An embodiment of the present invention will be described below with reference to the drawings. The present invention is not limited to the description of the embodiment below.

[0016] First Embodiment <Configuration of optical multiplexer> As shown in FIG. 1, the optical multiplexing device 1 according to this embodiment is a device that can multiplex a plurality of light beams, namely, light beams L10, L20, and L30, and output an output light beam L5. The light beams L10, L20, and L30 enter the optical multiplexing device 1 through the entrances 11a, 21a, and 31a, respectively, and are multiplexed inside the optical multiplexing device 1 to be output as output light beam L5. In this specification and claims, the plurality of light beams may be a plurality of light beams that are independent of wavelength. In other words, at least one set of the plurality of light beams may be light beams with the same wavelength. Note that the plurality of light beams may all have different wavelengths. In this embodiment, the light beams L10, L20, and L30 are not particularly limited, but may be, for example, the light beam L10 as red light, the light beam L20 as blue light, and the light beam L30 as green light.

[0017] 1 to 5, the position of the arrow indicating each light ray indicates the position of the optical axis of each light ray. Moreover, each of the above drawings is an exaggerated schematic diagram to easily show the relationship and angle between the light rays, and does not faithfully show the configuration of an actual optical multiplexing device.

[0018] The medium constituting the optical multiplexing device 1 is not particularly limited as long as it is a material capable of transmitting light with low loss, and may be, for example, glass, silicon, etc. The structure of the optical multiplexing device 1 may be manufactured, for example, by a known semiconductor manufacturing process. Furthermore, the medium may be a gas such as air, in which case the optical multiplexing device will have a hollow mirror-like form with the inner surface of the optical path being made up of a mirror surface.

[0019] The optical multiplexing device 1 has optical path units 10, 20, and 30 corresponding to the light beams L10, L20, and L30, respectively. In FIG. 1, an optical multiplexing device 1 that multiplexes light beams of three different wavelengths is shown. However, in the present disclosure, the number of multiplexed light beams may be two or more, and is not particularly limited. If it is desired to configure an optical multiplexing device that multiplexes light beams of two different wavelengths, it is sufficient to configure an optical multiplexing device that does not have the optical path unit 20 and in which the optical path unit 10 and the optical path unit 30 are connected. If it is desired to configure an optical multiplexing device that multiplexes light beams of four or more different wavelengths, it is sufficient to configure an optical multiplexing device that has the optical path unit 10, a plurality of optical path units 20 according to the number of light beams to be multiplexed, and the optical path unit 30.

[0020] In FIG. 1, the optical path unit 10 has a waveguide 11 and a waveguide 12. The waveguide 11 has an entrance 11a into which a light ray L10 is incident. The waveguide 11 and the waveguide 12 are connected at a substantially right angle in FIG. 1. A reflecting surface R1 is formed on the surface of the above-mentioned connection portion facing the waveguide 11. The light ray L10 incident from the entrance 11a passes through the inside of the waveguide 11 (light ray L11), is reflected by the reflecting surface R1, and enters the waveguide 12 (light ray L12). The angle of the reflecting surface R1 may be set so that the optical axis of the light ray L12 reflected by the reflecting surface R1 is guided in a direction along the optical path of the waveguide 12 and passes through approximately the center of the waveguide 12. Therefore, the angle at which the waveguide 11 and the waveguide 12 are connected can be any angle. However, the angle of the reflecting surface R1 needs to be set so as to exceed the critical angle of the medium (so as to cause total reflection at the reflecting surface), and the same applies to the following reflecting surfaces. The waveguide 12 is connected to the multiplexing path 22 of the optical path unit 20, and the light ray L12 is incident on the multiplexing path 22.

[0021] The optical path unit 10 does not need to have the waveguide 11. In this case, the light ray L10 can be made to be incident directly on the connection surface of the waveguide 12 with the waveguide 11 in Fig. 1. By having the optical path unit 10 have the waveguide 11, the position where the light beam is to be incident becomes clear as the shape of the waveguide, which makes it easier to assemble and adjust the actual device.

[0022] The optical path unit 10 does not need to have the reflecting surface R1. In this case, instead of the waveguides 11 and 12, one linear waveguide 12 may be used, and an entrance may be provided on the end face of the waveguide 12. On the other hand, since the optical path unit 10 has the reflecting surface R1, the position of the device that makes light enter the entrance 11a can be set to any position.

[0023] Here, referring to FIG. 3, the configuration of the device that makes light enter the entrance 11a will be described. As shown in FIG. 3, the divergent light L1 emitted from the light source B (maximum width of the light-emitting region: w40) is collected by the input optical system C1 composed of a collecting lens and the like. The collected light ray L10 enters the entrance 11a. In this case, if the lateral magnification of the input optical system C1 is β, the maximum width w41 of the light-emitting region image formed at the entrance 11a is w41=w40×β. Therefore, in order to make the light beam emitted from the light source B enter the entrance 11a without leakage, the width w3 of the entrance 11a needs to be larger than w41. When the light source B is a single mode LD, the width w3 of the entrance 11a is preferably 1.5 μm or more. When the light source B is a multimode LD, the width w3 of the entrance 11a is preferably 80 μm or more.

[0024] The optical path unit 20 has a waveguide 21 and a multiplexing path 22. The number of the optical path units 20 can be increased or decreased according to the number of lights to be multiplexed, and the optical path unit 20 may not be provided. The waveguide 21 has an entrance 21a into which the light beam L20 is incident. The waveguide 21 and the multiplexing path 22 are connected at a substantially right angle in FIG. 1. A reflecting surface R2 is formed on the surface of the above-mentioned connection part facing the waveguide 21. The above-mentioned connection part is further connected to the waveguide 12. The waveguide 12 and the multiplexing path 22 are connected so as to extend in the same direction. The angle at which the waveguide 12 and the waveguide 21 are connected and the angle at which the waveguide 21 and the multiplexing path 22 are connected can be any angle. The optical path unit 20 does not need to have a waveguide 21, like the optical path unit 10. In this case, the light ray L20 can be made to directly enter the connection surface between the waveguide 21 and the multiplexing path 22.

[0025] The light ray L20 incident from the light inlet 21a passes through the inside of the waveguide 21 (light ray L21), is reflected by the reflecting surface R2, and enters the multiplexing path 22 (light ray L22). The reflecting surface R2 is the reflecting surface that first reflects one of the light rays (light ray L21) incident from the light inlet. The angle of the reflecting surface R2 can be adjusted to any angle, similar to the reflecting surface R1. The multiplexing path 22 is connected to the multiplexing path 32 of the optical path unit 30.

[0026] The light ray L21 (one light ray) incident from the entrance 21a intersects with the light ray L12 (the other light ray) emitted from the previous optical path unit 10 in the first intersecting region F2 located at the connection portion between the waveguide 21 and the waveguide 12. Thereafter, the light ray L21 is reflected by the reflecting surface R2 and propagates to the multiplexing path 22 (light ray L22). The light ray L22 reflected by the reflecting surface R2 intersects with the light ray L12 (the other light ray) again in the second intersecting region F21 and is multiplexed (light ray L4). Thereafter, the light ray L4 enters the multiplexing path 32. In this specification and the claims, the positions where the light rays intersect and the positions where the light rays are reflected are positions based on the optical axes of the respective light rays.

[0027] 1, the second intersection region F21 is located at the rear end of the multiplexing path 22. However, this is not limited thereto, and the second intersection region F21 may be located within the multiplexing path 32. By locating the second intersection region F21 after the rear end of the multiplexing path 22, the number of reflections on the side surface of the optical path can be reduced, and the diffusion angle of the emitted light can be narrowed. The position of the second intersection region F21 can be set by adjusting the optical axis direction of the light ray L21, the angle of the reflecting surface R2, and the length of the multiplexing path 22.

[0028] As shown in FIG. 1, the multiplexing path 22 is configured such that the optical path width on the side connected to the subsequent multiplexing path is smaller than the optical path width on the side where the reflecting surface R2 is provided. Specifically, the optical path width of the multiplexing path 22 narrows linearly in proportion to the length between the reflecting surface R2 and the connection part with the multiplexing path 32. Since the multiplexing position is located near the connection part with the multiplexing path 32, the light beam reflected by the reflecting surface R2 propagates from the reflecting surface R2 to the multiplexing path 32 without being reflected by the side surface of the waveguide. On the other hand, it is known in principle that the diffusion angle of the emitted light increases when the number of reflections of the light beam on the side surface of the waveguide is large. Therefore, according to the above configuration, the diffusion angle of the emitted light can be narrowed in principle.

[0029] The optical path unit 30 has a waveguide 31 and a multiplexing path 32. The waveguide 31 has an entrance 31a into which the light ray L30 is incident. The waveguide 31 and the multiplexing path 32 are connected at a substantially right angle in FIG. 1. A reflecting surface R3 is formed on a surface of the connection portion facing the waveguide 31. The multiplexing path 22 is further connected to the connection portion. The multiplexing path 22 and the multiplexing path 32 are connected to extend in the same direction. The angle at which the multiplexing path 22 and the waveguide 31 are connected and the angle at which the waveguide 31 and the multiplexing path 32 are connected can be any angle.

[0030] A light ray L30 incident from the light inlet 31a passes through the inside of the waveguide 31 (light ray L31), is reflected by the reflecting surface R3, and enters the multiplexing path 32 (light ray L32). The reflecting surface R3 is the reflecting surface that first reflects one of the light rays (light ray L31) incident from the light inlet. The angle of the reflecting surface R3 can be adjusted to any angle, similar to the reflecting surface R1. A single exit port 32a is formed at the end of the multiplexing path 32.

[0031] The light ray L31 (one light ray) incident from the entrance 31a intersects with the light ray L4 (the other light ray) emitted from the previous optical path unit 20 in a first intersection region F3 located at the connection between the waveguide 31 and the multiplexing path 32. The light ray L31 is then reflected by the reflecting surface R3 and propagates to the multiplexing path 32 (light ray L32). The light ray L32 reflected by the reflecting surface R3 intersects with the light ray L4 (the other light ray) again in a second intersection region F4 and is multiplexed (light ray L5). The light ray L5 is then emitted to the outside from the exit 32a.

[0032] The second intersection region F4 of the optical path unit 30 is preferably set to the position of the exit port 32a as shown in Fig. 1. This makes it possible to narrow the diffusion angle of the emitted light (light ray L5). The position of the second intersection region F4 can be set by adjusting the optical axis direction of the light ray L31, the angle of the reflecting surface R3, and the length of the multiplexing path 32.

[0033] Here, referring to FIG. 2, a preferred embodiment in which two light beams (one light beam reflected by the reflecting surface and the other light beam emitted from the previous light path unit) are multiplexed in the second intersection region will be described. In FIG. 2, the light path unit 30 is taken as an example for description, but a similar configuration can also be applied to the light path unit 20. As shown in FIG. 2, the angle A between the two light beams when the two light beams are multiplexed is preferably 0.23° or less. This makes it possible to narrow the diffusion angle of the multiplexed light. The angle A can be adjusted by changing the reflecting surface inclination angle r3 of the reflecting surface R3 (the angle between the optical axis of the incident light from the entrance and the reflecting surface) and the length (light path length) w2 of the multiplexing path 32.

[0034] The length (optical path length) w1 of the waveguide 31 is preferably 1.5 mm or less. This makes it possible to minimize the loss of incident light. The same applies to the first optical path unit and the second optical path unit.

[0035] Although the preferred embodiments of the present invention have been described above, the contents of the present invention are not limited to the above-described embodiments and can be modified as appropriate. EXAMPLES

[0036] The present invention will be described in more detail below based on examples, but the present invention is not limited to these examples.

[0037] [Example 1] In an optical multiplexing device having the same configuration as the optical multiplexing device 1 according to the first embodiment, optical design software ZEMAX (registered trademark) (manufactured by ZEMAX Development Corporation) was used to perform optical simulation. The configuration of the optical multiplexing device of the specific example 1 is shown below. Red light was used as the light beam L10, blue light was used as the light beam L20, and green light was used as the light beam L30 (input lens: FLGSRSA21A manufactured by Alps Alpine Co., Ltd.). The length w1 (length w1 in FIG. 2) of the waveguides 11, 21, and 31 of each optical path unit was 1.259 mm. The length w2 (length w2 in FIG. 2) of the waveguide 12 and the multiplexing path 22 was 1.5 mm. The length (length w2 in FIG. 2) of the multiplexing path 32 was 1.62 mm. The width w3 (length w3 in FIG. 2) of the waveguides 11, 12, 21, and 31 of each optical path unit was 5 μm. The maximum width (width on the front side) of the multiplexing path 22 and the multiplexing path 32 was 10 μm, and the minimum width (width on the rear side) was 5 μm. The depth (length in the direction perpendicular to the paper surface in FIG. 1) of each waveguide and multiplexing path was 5 μm. That is, the cross section of the emission port was set to 5 μm x 5 μm. In the multiplexing path 22, the multiplexing angle with other blue light beams (multiplexing angle A in FIG. 2) was 0.191° (reflection surface inclination angle of reflecting surface R2: 45.096°). In the multiplexing path 32, the multiplexing angle with other green light beams (multiplexing angle A in FIG. 2) was 0.177° (reflection surface inclination angle of reflecting surface R3: 45.089°).

[0038] A detector (detector 1) was placed at a position immediately after the emission of the emission port of the optical multiplexing device of Example 1. An output lens (Edmund #84127, manufactured by Edmund Optics Japan Co., Ltd.) was placed at a position on the optical axis 2.6 mm away from the emission port, and a detector (detector 2) was placed on the first surface (incident surface). A detector (detector 3) was placed at a position on the optical axis 17.547 mm away from the first surface. The intensity distribution of the output light detected by each detector is shown in FIG. 5. The vertical and horizontal axes of FIGS. 5 to 9 correspond to the detector size (unit: mm), and the center (vertical axis = 0, horizontal axis = 0) corresponds to the position of the optical axis. In each figure, the darker areas indicate areas with high intensity of output light.

[0039] [Examples 2 to 4] Except for the configuration of the optical multiplexing device shown in Table 1, the optical multiplexing devices according to Examples 2 to 4 were configured in the same manner as in Example 1. Example 3 was configured without providing the waveguides 11, 21, and 31. In addition, an optical simulation was performed using the optical multiplexing devices of Examples 2 to 4 with the same arrangement of detectors and output lenses as in Example 1. The intensity distribution of the output light is shown in Example 2: FIG. 7, Example 3: FIG. 8, and Example 4: FIG. 9, respectively.

[0040] [Comparative Example 1] The configuration of the optical multiplexing device 1b according to the comparative example 1 is shown in FIG. 4. As shown in FIG. 4, the optical multiplexing device 1b has an optical path unit 10B, an optical path unit 20B, and an optical path unit 30B. Each optical path unit is provided with a waveguide 11B, 21B, and 31B (optical path length: 1.259 mm) into which the light beam L10b (red light), the light beam L20b (blue light), and the light beam L30b (green light), respectively, are incident. The configuration of the optical path unit 10B is the same as that of the optical path unit 10, and has a waveguide 12B. The configurations of the optical path units 20B and 30B are different from those of the optical path units 20 and 30, in that the incident light (one light beam) is reflected before passing through the first intersection region and is multiplexed with the other light beam. In the above configuration, there is a limit to making the multiplexing angle sufficiently small. The multiplexing paths 22B and 32B multiplex multiple light beams with expanded waveguide widths W22b and W32b (both 18 μm). The waveguide width is then reduced to width wb1 (6 μm). The multiplexing angles r2b and r3b are both 1°. The multiplexed light beam L6 is emitted from the exit port 32b. Other details of each component are shown in Table 1. However, the symbols in Table 1 (W1 to W3, etc.) use the symbols of the optical multiplexing device 1 corresponding to the configuration of Comparative Example 1.

[0041] Using the optical multiplexing device 1b according to the above-mentioned Comparative Example 1, an optical simulation was performed with the same arrangement of the detector and output lens as in Example 1. The intensity distribution of the output light is shown in FIG.

[0042] From the results of Figures 5 and 6, for example, when comparing the spread of the light beam on the detector 2, it is clear that the spread of the light beam in Example 1 is narrower than that in Comparative Example 1, and therefore the emitted light diffusion angle is narrower than that in the Comparative Example.

[0043] [Table 1]

[0044] The light intensity values ​​reaching each detector in the above Examples 1 to 4 and Comparative Example 1 are shown in Table 2 below. In Table 2, the waveguide transmittance (%) means the light intensity value of light reaching detector 1 / light intensity value of the light source (%). The output lens conversion efficiency (%) means the light intensity value of light reaching detector 3 / light intensity value of light reaching detector 2 (%). The total light utilization efficiency (%) means the light intensity value of light reaching detector 3 / light intensity value of the light source (%).

[0045] [Table 2]

[0046] As shown in Table 2, compared to the optical multiplexer of Comparative Example 1, the optical multiplexers of each embodiment are clearly superior in terms of waveguide transmittance (%), output lens conversion efficiency (%), and total light utilization efficiency (%). [Explanation of symbols]

[0047] 1 Optical multiplexer 11a, 21a, 31a Inlet F2, F3 First Intersection Area F21, F4 Second intersection area 22, 32 Combined 11, 21, 31 Waveguide 32a Output port A Combined angle 10 First Optical Path Unit 20 Second Optical Path Unit 30 Third Path Unit

Claims

1. An optical multiplexing device capable of multiplexing a plurality of light beams, a plurality of entrance ports through which the plurality of light beams are respectively incident; a single exit port through which light obtained by combining the plurality of light beams is emitted; a multiplexing path through which the plurality of light beams are multiplexed; a first intersection region where one light ray incident from the entrance intersects with another light ray; a reflecting surface that reflects the one light ray that has passed through the first intersection region; a second intersection region where the one light ray reflected by the reflecting surface intersects with the other light ray again; a rear end of the multiplexing path is connected to another multiplexing path at a subsequent stage or is provided with the output port; an inclination angle of the reflecting surface with respect to the light beam incident from the light entrance is set so that the second intersecting region is a connection portion with the other multiplexing path or a position of the light exit; An optical multiplexing device, wherein a multiplexing angle formed between the one light beam reflected by the reflecting surface and the other light beam is 0.23° or less.

2. a waveguide having the entrance and a multiplexing path connected to the waveguide at a predetermined angle; 2. The optical multiplexer according to claim 1, wherein the length of said waveguide is 1.5 mm or less.

3. a first optical path unit having the entrance; a second optical path unit having the entrance, the first intersection region, the reflecting surface, and the second intersection region; a third optical path unit having the entrance, the first intersection region, the reflecting surface, the second intersection region, and the exit, 2. The optical multiplexing device according to claim 1, wherein one or more second optical path units are provided as needed.

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