阅读说明：本技术 光合波器、光源模块、二维光扫描装置以及图像投射装置 (Optical multiplexer, light source module, two-dimensional optical scanning device, and image projection device ) 是由 山田祥治 胜山俊夫 于 2018-11-08 设计创作，主要内容包括：涉及光合波器、光源模块、二维光扫描装置以及图像投射装置,在不设置附加的光衰减要素的情况下将来自光源的光束强度衰减至期望的值。对设置于光合波部的光耦合部进行设定,使得从多个光源输入到各个输入光波导路的光束的强度在从输出光波导路作为合波光而输出的阶段在5dB～40dB的范围内衰减。(Disclosed are an optical multiplexer, a light source module, a two-dimensional optical scanning device, and an image projection device, which attenuate the intensity of a light beam from a light source to a desired value without providing an additional light attenuation element. The optical coupling section provided in the optical combiner is set so that the intensity of the light beam input from the plurality of light sources to each input optical waveguide is attenuated within a range of 5dB to 40dB at the stage of outputting as combined light from the output optical waveguide.)

1. An optical multiplexer, comprising:

a plurality of input optical waveguides including at least a 1 st input optical waveguide and a 2 nd input optical waveguide; and

an output optical waveguide having a light combining section, at least a part of the output optical waveguide being a linear optical waveguide,

the 1 st input optical waveguide has a 1 st optical coupling section optically coupled to the output optical waveguide in the optical coupling section,

the 2 nd input optical waveguide has a 2 nd optical coupling section optically coupled to the output optical waveguide in the optical coupling section,

the 1 st optical coupling section is set so that the attenuation of the light beam input to the 1 st input optical waveguide with respect to the light beam output from the output optical waveguide is in a range of 5dB to 40dB,

the 2 nd optical coupling section is set so that the attenuation of the light beam input to the 2 nd input optical waveguide with respect to the light beam output from the output optical waveguide is in a range of 5dB to 40 dB.

2. The optical combiner of claim 1,

the output optical waveguide is a linear optical waveguide at least in a region other than the vicinity of the emission end.

3. The optical combiner of claim 2, wherein,

the output optical waveguide is inclined at an angle of 85 DEG to 95 DEG with respect to the linear optical waveguide in the vicinity of the emission end.

4. The optical combiner according to any one of claims 1 to 3,

the plurality of input optical waveguides have a 3 rd input optical waveguide,

the 3 rd input optical waveguide also serves as an optical waveguide on the incident end side of the output optical waveguide,

the 1 st input optical waveguide includes a 3 rd optical coupling section for splitting a light beam incident on the 1 st input optical waveguide at a preceding stage of optical coupling with the optical coupling section.

5. The optical combiner of claim 4,

the 1 st optical coupling section is separated into two optical coupling sections with the 2 nd optical coupling section interposed therebetween.

6. The optical combiner according to any one of claims 1 to 3,

the plurality of input optical waveguides have a 3 rd input optical waveguide,

the 3 rd input optical waveguide includes a 3 rd optical coupling section optically coupled to the 2 nd input optical waveguide at a stage before the 2 nd optical coupler.

7. The optical combiner according to any one of claims 1 to 3,

the plurality of input optical waveguides have a 3 rd input optical waveguide,

the 3 rd input optical waveguide includes a 3 rd optical coupling unit optically coupled to the output optical waveguide in the optical coupling unit.

8. The optical combiner according to any one of claims 4 to 7,

the light combining unit combines at least three primary colors of red light, blue light, and green light.

9. The optical combiner according to any one of claims 1 to 8,

the waveguide direction in the vicinity of the input ends of the plurality of input optical waveguides is inclined at an angle of 85 ° to 95 ° with respect to the linear optical waveguide.

10. The optical combiner according to any one of claims 1 to 8,

the waveguide direction near the input end of at least one of the plurality of input optical waveguides is inclined at an angle of 85 ° to 95 ° with respect to the linear optical waveguide, and the waveguide direction near the input end of the remaining input optical waveguide among the plurality of input optical waveguides is inclined at an angle of 85 ° to 95 ° with respect to the linear optical waveguide so as to face the waveguide direction near the input end of the at least one input optical waveguide.

11. A light source module, having:

an optical combiner according to any one of claims 1 to 10; and

a plurality of light sources that incident the light beam to the optical combiner.

12. The light source module of claim 11,

a lens is provided between the plurality of light sources and the plurality of input optical waveguides of the optical combiner.

13. The light source module of claim 11 or 12,

the plurality of light sources are blue, green, and red semiconductor lasers.

14. The light source module of claim 11 or 12,

the plurality of light sources are blue light emitting diodes, green light emitting diodes, and red light emitting diodes.

15. The light source module of claim 11 or 12,

the plurality of light sources are light sources emitted from a plurality of optical fibers.

16. A two-dimensional optical scanning device, comprising:

the light source module of any one of claims 11 to 15; and

and a two-dimensional light scanning mirror device for two-dimensionally scanning the combined light from the light source module.

17. An image projection apparatus having:

the two-dimensional optical scanning apparatus of claim 16; and

and an image forming unit that projects the multiplexed light scanned by the two-dimensional light scanning mirror device onto a projection surface.

Technical Field

The present invention relates to an optical multiplexer, a light source module, a two-dimensional optical scanning device, and an image projection device, and for example, to a configuration for attenuating the intensity of a light beam from a light source to a desired value without providing an additional light attenuation element.

Background

Conventionally, various types of light beam combining light source devices have been known as a device for combining a plurality of light beams such as laser beams and emitting the combined light beam as one light beam. Among them, a light beam combining light source device obtained by combining a semiconductor laser and an optical waveguide type combiner has advantages of downsizing the device and reducing power consumption, and is applied to a laser beam scanning type color image projection device (for example, see patent documents 1 to 6).

As a conventional light beam combining light source obtained by combining a semiconductor laser and an optical waveguide type optical multiplexer, for example, a light beam combining light source for combining laser beams of three primary colors is known as shown in patent document 3.

Fig. 19 is a conceptual configuration diagram of a conventional optical multiplexer of the present inventors (see patent document 2). The optical coupler includes input optical waveguides 23 to 25 each including a core layer and a cladding layer, an optical multiplexer 40, and an output optical waveguide 27, and the input optical waveguide 23 is optically coupled to the input optical waveguide 24 by optical couplers 41 and 42 of the optical multiplexer 40. The input optical waveguide 25 is optically coupled to the input optical waveguide 24 in the optical coupler 43 of the optical multiplexer 40.

Blue semiconductor laser chips 31, green semiconductor laser chips 32, and red semiconductor laser chips 33 are provided at the incident ends of the input optical waveguides 23 to 25 corresponding to the respective colors. Here, the light beams propagate through the core layers of the input optical waveguides 23 to 25, are combined by the optical combiner 40, and are emitted as combined light from the emission end of the output optical waveguide 27, which is an extension of the input optical waveguide 24.

Fig. 20 is a schematic perspective view of a two-dimensional optical scanning device proposed by the present inventors (see patent document 6), and it is sufficient to provide an optical multiplexer 62 on a substrate 61 on which a movable mirror portion 63 is formed, and to couple the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 to the optical multiplexer 62. Since the movable mirror portion 63 is downsized, even when it is integrated with a light source that generates a light beam, the entire size after integration can be reduced. In particular, in the case of a light source in which a light beam is emitted from a semiconductor laser chip or an optical multiplexer, the semiconductor laser chip or the optical multiplexer may be formed on a Si substrate or a metal plate substrate, and thus the light source and the two-dimensional light scanning mirror device are formed on the substrate, which has an effect that the overall size after integration can be reduced.

Fig. 21 is a schematic perspective view of an image projection apparatus proposed by the present inventors (see patent document 6), and the image projection apparatus may be configured by combining the two-dimensional scanning apparatus described above, a two-dimensional scanning control unit that applies a two-dimensional light scanning signal to the electromagnetic coil 64 to perform two-dimensional scanning of the light emitted from the light source, and an image forming unit that projects the scanned light emitted onto a projection surface. In addition, as the image projection apparatus, a glasses type retina scanning display is typical

In the past, in such a beam combining light source device, efforts have been made to develop a device for maximizing the transmission efficiency from the output of the semiconductor laser to the output of the light source device. By improving the coupling efficiency between the semiconductor laser and the optical waveguide of the optical multiplexer and the optical multiplexing efficiency, the transmission efficiency can be increased to 90% or more. In this case, when the current semiconductor laser is operated at the rated output, the output of the combiner is several mW.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2008-242207

Patent document 2: japanese patent laid-open publication No. 2013-195603

Patent document 3: international publication No. 2015/170505

Patent document 4: specification of U.S. patent application publication No. 2010/0073262

Patent document 5: international publication No. 2017/065225

Patent document 6: japanese patent laid-open publication No. 2018-072591

Non-patent document

Non-patent document 1: IEEE Photonics technology Letters, Vol.19, No.5, pp,330-

Disclosure of Invention

Problems to be solved by the invention

On the other hand, in a retina scan type display, which is a main application target of the multiplex light source device, the light power finally incident on the pupil of the observer is about 10 μ W. In the case of driving a semiconductor laser with a small current to reduce the pupil incident light power, there is a problem that the optical dynamic range is narrowed due to a natural light emitting component. On the other hand, if the minimum level drive current is set to be significantly smaller than the threshold current in order to suppress the natural light emission component, there is a problem that high-speed optical modulation becomes difficult. That is, although the drive current of the semiconductor laser changes depending on the brightness of each pixel of an image to be displayed, it is desirable to set the range of the change in the drive current to be equal to or greater than the threshold current in order to reliably perform high-speed modulation. However, in this case, even if the driving current is set to the minimum value (threshold current value) to display the lowest luminance (black level), there is residual light due to natural light emission, and the ratio of the light amount (white level) when the driving current is maximum to the residual light becomes the contrast. When the maximum value of the drive current is sufficiently large, the amount of white light is large, and therefore a desired contrast can be sufficiently ensured. However, since the optical power required in the retina scan type display is small, the maximum value of the drive current needs to be set low. When the maximum value of the drive current is set low, the white-level light amount becomes small, while the residual light amount at the black level does not change when the minimum value of the drive current is kept at the threshold value, and therefore the contrast is lowered. When the maximum value of the drive current is set low, it is necessary to set the drive current of the pixel close to the black level to a threshold value or less and reduce the natural light emission amount in order to improve the contrast. In this case, the semiconductor laser is driven at a threshold current or higher in the case of a normal pixel, and the drive current is temporarily switched to a threshold current or lower only when a pixel close to the black level is displayed. The ratio depends on the image content.

As another method for reducing the optical power, there is a method of inserting an optical attenuation element such as an optical absorber, a reflector, or an optical axis offset coupling section into the optical path. In this case, in addition to the additional element that generates optical attenuation, there is a concern that reliability may be degraded due to a characteristic change or alignment variation of the additional optical element.

An object of the present invention is to attenuate the intensity of a light beam from a light source to a desired value without providing an additional optical attenuation element in an optical multiplexer having an input optical waveguide, an output optical waveguide, and an optical multiplexer unit.

Means for solving the problems

In one aspect, an optical multiplexer includes: a plurality of input optical waveguides including at least a 1 st input optical waveguide and a 2 nd input optical waveguide; and an output optical waveguide having an optical coupling unit, at least a part of the output optical waveguide being a linear optical waveguide, wherein the 1 st input optical waveguide has a 1 st optical coupling unit optically coupled to the output optical waveguide in the optical coupling unit, the 2 nd input optical waveguide has a 2 nd optical coupling unit optically coupled to the output optical waveguide in the optical coupling unit, the 1 st optical coupling unit is set so that an attenuation amount of a light beam input to the 1 st input optical waveguide with respect to a light beam output from the output optical waveguide is in a range of 5dB to 40dB, and the 2 nd optical coupling unit is set so that an attenuation amount of a light beam input to the 2 nd input optical waveguide with respect to a light beam output from the output optical waveguide is in a range of 5dB to 40 dB.

In another aspect, the light source module includes the optical multiplexer and a plurality of light sources that make the light beam incident on the optical multiplexer.

In another aspect, the two-dimensional optical scanning device includes the light source module and a two-dimensional optical scanning mirror device that two-dimensionally scans the combined light from the light source module.

In another aspect, the image projection device includes the two-dimensional optical scanning device described above and an image forming unit that projects the combined light scanned by the two-dimensional optical scanning mirror device onto a projection surface.

Effects of the invention

As one side, in an optical multiplexer having an input optical waveguide, an output optical waveguide, and an optical multiplexer, the intensity of a light beam from a light source can be attenuated to a desired value without providing an additional optical attenuation element. By using the optical multiplexer, a retina scanning type display having high reliability in contrast can be obtained.

Drawings

Fig. 1 is a plan view of a concept of an optical multiplexer according to an embodiment of the present invention.

Fig. 2 is a conceptual configuration diagram of an optical multiplexer according to embodiment 1 of the present invention.

Fig. 3 is an explanatory diagram of the propagation state of the red light beam in the optical multiplexer according to embodiment 1 of the present invention.

Fig. 4 is an explanatory diagram of a propagation state of a green light beam in the optical multiplexer according to embodiment 1 of the present invention.

Fig. 5 is an explanatory diagram of a propagation state of a blue light beam in the optical multiplexer according to embodiment 1 of the present invention.

Fig. 6 is a plan view of a concept of an optical multiplexer according to embodiment 2 of the present invention.

Fig. 7 is an explanatory diagram of the propagation state of the red light beam in the optical multiplexer according to embodiment 2 of the present invention.

Fig. 8 is an explanatory diagram of the propagation state of the green light beam in the optical multiplexer according to embodiment 2 of the present invention.

Fig. 9 is an explanatory diagram of a propagation state of a blue light beam in the optical multiplexer according to embodiment 2 of the present invention.

Fig. 10 is a plan view of a concept of an optical multiplexer according to embodiment 3 of the present invention.

Fig. 11 is a plan view of a concept of an optical multiplexer according to embodiment 4 of the present invention.

Fig. 12 is a plan view of a concept of an optical multiplexer according to embodiment 5 of the present invention.

Fig. 13 is a plan view of a concept of an optical multiplexer according to embodiment 6 of the present invention.

Fig. 14 is a plan view of a concept of an optical multiplexer according to embodiment 7 of the present invention.

Fig. 15 is a conceptual configuration diagram of a light source module according to embodiment 8 of the present invention.

Fig. 16 is a conceptual configuration diagram of a light source module according to embodiment 9 of the present invention.

Fig. 17 is a conceptual configuration diagram of a light source module according to embodiment 10 of the present invention.

Fig. 18 is a conceptual configuration diagram of a light source module according to embodiment 11 of the present invention.

Fig. 19 is a plan view of a concept of a conventional optical multiplexer of the present inventors.

Fig. 20 is a schematic perspective view of an example of a conventional two-dimensional optical scanning device.

Fig. 21 is a schematic perspective view of a conventional image forming apparatus.

Detailed Description

Here, an example of an optical multiplexer according to an embodiment of the present invention will be described with reference to fig. 1. Fig. 1 is a plan view of a concept of an optical multiplexer according to an embodiment of the present invention. In addition, here, a light source 11 is added₁～11₃But is illustrated in the form of a light source module. As shown in fig. 1, an optical multiplexer according to an embodiment of the present invention includes at least: a plurality of input optical waveguides 4-6 including a 1 st input optical waveguide 4 and a 2 nd input optical waveguide 5; and an output optical waveguide 2 having a light combining section 3, at least a part of the output optical waveguide 2 being a linear optical waveguide. The 1 st input optical waveguide 4 has a 1 st optical coupling section 7 optically coupled with the output optical waveguide 2 in the optical multiplexer section 3₁、7₂The 2 nd input optical waveguide 5 includes a 2 nd optical coupling section 8 optically coupled with the output optical waveguide 2 in the optical combining section 3. In addition, as the light source 11₁～11₃Semiconductor lasers are typical light sources, but may also be light sources by means of Light Emitting Diodes (LEDs) or optical fibers.

In this case, the 1 st optical coupling section 7 is optically coupled to₁、7₂The attenuation amount of the light beam input to the 1 st input optical waveguide 4 with respect to the light beam output from the output optical waveguide 2 is set to be in the range of 5dB to 40dB in total.The 2 nd optical coupling section 8 is set so that the attenuation of the light beam input to the 2 nd input optical waveguide 5 with respect to the light beam output from the output optical waveguide 2 is in the range of 5dB to 40 dB.

I.e. although dependent on the rated output P of the semiconductor laser_Id(1-10 mW) and a coupling loss α with an optical waveguide_cpAnd the transmission loss alpha of the display optical system_sysHowever, the amount of light attenuation α from the incident power to the input optical waveguides 4 to 6 to the optical combining output power from the output optical waveguide 2_mpx(＝10log(P_ld/P_dp)-α_cp-α_sys) The required value of (A) is in the range of 5dB to 40dB, more preferably 10dB to 30 dB. Wherein, P_dpThe required display optical power is about 1 muW-10 muW. In addition, the loss (. alpha.) is_cp+α_sys) Is 15dB or less. If the attenuation is less than 5dB, even at P_IdIs minimum 1mW and loss (alpha)_cp+α_sys) At maximum 15dB, the optical power of the display will exceed the required range P_dpThe value of (c). On the other hand, if the attenuation amount is greater than 40dB, a desired amount of light cannot be obtained. The end of each optical waveguide of the optical multiplexer unit 3 is substantially extended to the end of the substrate 1 in such a manner that the output light is not mixed with the multiplexed light (the same applies to the drawings of the following embodiments). The number of input optical waveguides is arbitrary, and two or four or more input optical waveguides may be used. The attenuation ratio is determined by configuring each optical coupling part (7)₁、7₂8, 10) and the interval between the optical waveguides constituting the directional coupler.

The output optical waveguide 2 may be a linear optical waveguide at least in a region other than the vicinity of the emission end, and may be inclined at an angle of 85 ° to 95 ° with respect to the linear optical waveguide (2) in the vicinity of the emission end, like the bent portion 12 shown by a broken line in the figure. Thus, by providing the inflection portion 12, the optical coupling portion 7 of the slave optical coupling portion 3 can be reliably prevented from being affected₁、7₂8 stray light leaking outOverlapping the multiplexed light.

As the plurality of input optical waveguides, a 3 rd input optical waveguide 6 may be provided, and the 3 rd input optical waveguide 6 may also serve as an optical waveguide on the incident end side of the output optical waveguide 2. The 1 st input optical waveguide 4 is provided with a 3 rd optical coupling 10 for splitting the light beam incident on the 1 st input optical waveguide 4 at a stage before the optical coupling with the optical multiplexer 3. In this way, the optical waste optical waveguide 9 optically coupled to the 1 st input optical waveguide 4 is provided. In this case, the 1 st optical coupling section may be separated into two optical multiplexing sections 7 with the 2 nd optical multiplexing section 8 interposed therebetween₁、7₂。

The plurality of input optical waveguides may have a 3 rd input optical waveguide 6, and the 3 rd input optical waveguide 6 may be provided with a 3 rd optical coupling section optically coupled to the 2 nd input optical waveguide 5 in a stage before the 2 nd optical coupler 5. Alternatively, the plurality of input optical waveguides may have a 3 rd input optical waveguide 6, and the 3 rd input optical waveguide 6 may be provided with a 3 rd optical coupling section for optically coupling with the output optical waveguide 2 in the optical combining section 3.

As the light combining unit 2, a light combining unit that combines at least three primary colors of red light, blue light, and green light is typical. In this case, the order of optical coupling with the output optical waveguide 2 is arbitrary, and for example, the light source 11 may be coupled₁Blue, red or green may be used.

Alternatively, the waveguide directions near the input ends of the plurality of input optical waveguides 4 to 6 may be inclined at an angle of 85 DEG to 95 DEG with respect to the linear optical waveguide 2. With this arrangement, the dimension of the optical multiplexer in the longitudinal direction can be reduced, and the influence of stray light from the light source can be reduced. The output end of the output optical waveguide 2 may be inclined at 90 ° with respect to the optical axis of the linear optical waveguide 2 of the optical multiplexer 3, but 85 ° to 95 ° is adopted in consideration of manufacturing errors and the like.

May be a plurality of light sources 11₁～11₃Is disposed on one side of the substrate 1 such that the waveguide direction and the optical multiplexer unit are in the vicinity of the input ends of the plurality of input optical waveguides 4 to 6The optical axis of the linear optical waveguide (2) of 3 forms an angle of 85 DEG to 95 deg. Alternatively, a plurality of light sources 11 may be provided₁～11₃At least one (11) of₁) Is arranged at the 1 st side of the substrate 1, and the rest of the light sources (11)₂、11₃) And a 2 nd side opposed to the 1 st side, wherein the waveguide direction in the vicinity of the input ends of the plurality of input optical waveguides 4-6 and the optical axis of the linear optical waveguide 2 of the optical multiplexer 3 are arranged at an angle of 85 DEG-95 deg.

The substrate 1 may be any substrate such as an Si substrate, a glass substrate, a metal substrate, or a plastic substrate. Further, as the material of the lower cladding layer, the core layer, and the upper cladding layer, SiO may be used₂A glass-based material, but a material other than this, for example, a transparent plastic such as acrylic resin or other transparent material may be used.

In order to form the light source module, the various optical combiners described above and a plurality of light sources 11 for emitting light beams to the optical combiners may be combined as shown in fig. 1₁～11₃. As the light source 11 in this case₁～11₃Semiconductor lasers are typical, but may also be light emitting diodes. In addition, a plurality of light sources 11 may be provided₁～11₃Lenses are provided between the optical multiplexer and the plurality of input optical waveguides 4 to 6. Instead of the light source 11, a light source device in which an optical fiber output end is provided at the position of the light source and the output light from the optical fiber is guided to the optical multiplexer 3 may be used₁～11₃。

The optical multiplexer 62 of the two-dimensional optical scanning device shown in fig. 20 and the various optical multiplexers described above may be combined to form a two-dimensional optical scanning device. In order to form an image projection apparatus, as shown in fig. 21, the two-dimensional scanning apparatus described above, a two-dimensional scanning control unit that applies a two-dimensional optical scanning signal to the electromagnetic coil 64 to perform two-dimensional scanning of the light emitted from the light source, and an image forming unit that projects the scanned light emitted onto the projection surface may be combined. As an image projection apparatus, a glasses-type retina scanning display (for example, see patent document 2) is typical. The image projection device according to the embodiment of the present invention is worn on the head of a user using, for example, a glasses-type wearing tool (see, for example, patent document 4).

The structure of each optical waveguide may be a structure in which each core layer is covered with a common upper cladding layer, a structure in which each core layer is covered with a separate upper cladding layer, or a structure in which each core layer is covered with a separate lower cladding layer and a separate upper cladding layer.

Example 1

Here, an optical multiplexer according to embodiment 1 of the present invention will be described with reference to fig. 2 to 5. Fig. 2 is a conceptual configuration diagram of an optical multiplexer according to embodiment 1 of the present invention, in which fig. 2 (a) is a schematic plan view and fig. 2 (b) is a cross-sectional view of an input end side. The optical multiplexer according to embodiment 1 of the present invention is an optical multiplexer in which an optical waste optical waveguide is provided in a conventional optical multiplexer shown in fig. 19, and here, a light source is added and illustrated as a light source module for easy understanding of the present invention. As shown in fig. 2 (a), a light beam from the blue semiconductor laser chip 31 is input to the input optical waveguide 23, a light beam from the green semiconductor laser chip 32 is input to the input optical waveguide 24, and a light beam from the red semiconductor laser chip 33 is input to the input optical waveguide 25. The input optical waveguides 23 to 25 are connected to the optical waveguide of the optical multiplexer 40, and the combined light combined by the optical multiplexer 40 is output from the output end of the output optical waveguide 27. The output end of the output optical waveguide 27 may be a simple cleavage plane or the like, but the beam shape may be controlled using, for example, a spot size converter or the like.

As shown in FIG. 2 (b), each optical waveguide was formed by providing 20 μm thick SiO on a 1mm thick (100) plane Si substrate 21₂Layer 22 as a lower cladding layer, for the SiO₂Ge-doped SiO on layer 22₂The glass was etched to form a core layer having a width x height of 2 μm x 2 μm, on which a layer of SiO having a thickness of 9 μm was provided₂Upper cladding layer 26 (SiO) of layer constitution₂Thickness on the layer 22 is 11 μm), thereby forming the input optical waveguide 2325, the optical waste optical waveguide 28, and the output optical waveguide 27 of the optical multiplexer 40. In this case, the difference in refractive index between the core layer and the clad layer was 0.5%.

Here, the photosynthetic wave unit 40 has a length of 3mm and a width of 3.1 mm. The length of the optical coupling portion 41 is 350 μm, the length of the optical coupling portion 42 is 240 μm, the length of the optical coupling portion 43 is 200 μm, and the length of the optical coupling portion 44 is 1200 μm. The emission wavelength of the blue semiconductor laser chip 31 is 450nm, the emission wavelength of the green semiconductor laser chip 32 is 520nm, and the emission wavelength of the red semiconductor laser chip 33 is 638 nm.

The exit ports of the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 are installed so as to coincide with the entrance ports of the input optical waveguides 23 to 25 in the lateral direction and the height direction, respectively, and the interval from the entrance ends of the input optical waveguides 23 to 25 is 10 μm.

Fig. 3 is an explanatory view of the propagation state of a red light beam in the optical multiplexer according to embodiment 1 of the present invention, fig. 3 (a) is a view of imaging the simulation result, and fig. 3 (b) is a view of copying fig. 3 (a). Although 73% of the incident power of the red light beam entering the input optical waveguide 25 is shifted to the output optical waveguide 27 by the optical coupling section 43, most of the power immediately thereafter is shifted to the second half of the input optical waveguide 23 by the optical coupling section 42, and finally the output from the optical power optical waveguide 27 is 3.5% of the incident power (the light attenuation amount is 14.6 dB).

Fig. 4 is an explanatory view of the propagation state of a green light beam in the optical multiplexer according to embodiment 1 of the present invention, fig. 4 (a) is a view of imaging the simulation result, and fig. 4 (b) is a view of copying fig. 4 (a). Most of the incident power of the green light beam entering the input optical waveguide 24 is shifted to the second half of the input optical waveguide 23 by the optical coupling sections 41 and 42, and finally the output from the output optical waveguide 27 is 5.1% of the incident power (the optical attenuation amount is 12.9 dB).

Fig. 5 is an explanatory diagram of the propagation state of the blue light beam in the optical multiplexer according to embodiment 1 of the present invention, fig. 5 (a) is a diagram of imaging the simulation result, and fig. 5 (b) is a diagram of copying fig. 5 (a). 89% of the incident power of the blue light beam incident on the input optical waveguide 23 is transferred to the optical waste optical waveguide 28 in the optical coupling section 44, and 4.7% of the incident power (the optical attenuation amount is 13.3dB), which is about half of the optical power remaining in the input optical waveguide 23, is transferred to the output optical waveguide 27 via the optical coupling section 41 and the optical coupling section 42, and is output as combined light.

In example 1 of the present invention, the optical waste optical waveguide 28 with the optical coupling section 44 is provided only in the optical multiplexer of the conventional example of fig. 19 in which the manufacturing process is established and the characteristics are confirmed, and the coupling coefficient of the known optical coupler is set to substantially half, so that the attenuation amount with respect to the blue light beam can be independently set, and the design is easy. In example 1, the output optical waveguide 27 may be bent at the output end as indicated by the broken line in fig. 1.

Example 2

Next, an optical multiplexer according to embodiment 2 of the present invention will be described with reference to fig. 6 to 9. Fig. 6 is a plan view of a concept of an optical multiplexer according to embodiment 2 of the present invention. Here, too, a light source is added and illustrated as a light source module for the sake of easy invention. As shown in fig. 6, the optical multiplexer unit 45 forms an optical multiplexer together with the input optical waveguides 23 to 25 and the output optical waveguide 27. The light emitted from the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 is not directly coupled to the output optical waveguide 27, and the combined light output is moved from the input optical waveguides 23 to 25 to the output optical waveguide 27 through the optical combining section 45.

The blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 as light sources are arranged on the incident end surface side of the optical multiplexer. The light beams emitted from the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 propagate through the optical waveguides 23 to 25, respectively, and are guided to the optical multiplexer 45. In addition, the output end of the output optical waveguide 27 may be a simple cleavage plane or the like, and for example, a spot size converter or the like may be used to control the beam shape.

Each optical waveguide was formed by disposing SiO having a thickness of 20 μm on a (100) plane Si substrate having a thickness of 1mm₂The layer is used as a lower cladding layer and is arranged on SiO₂The Ge-doped SiO2 glass on the layer is etched to form a core layer with a width x height of 2 μm x 2 μm, on which a layer of SiO with a thickness of 9 μm is provided on the core layer₂The input optical waveguides 23 to 25, the optical waveguides of the optical multiplexer 45, and the output optical waveguide 27 are formed by an upper cladding layer. In this case, the difference in refractive index between the core layer and the clad layer was 0.5%. Here, the dimensions of the photosynthetic wave part 45 are 2mm in length and 3.1mm in width.

The length of the optical coupling portion 46 was 100 μm, the length of the optical coupling portion 47 was 6 μm, and the length of the optical coupling portion 48 was 12 μm. The emission wavelength of the blue semiconductor laser chip 31 is 450nm, the emission wavelength of the green semiconductor laser chip 32 is 520nm, and the emission wavelength of the red semiconductor laser chip 33 is 638 nm.

The exit ports of the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 are installed so as to coincide with the entrance ports of the input optical waveguides 23 to 25 in the lateral direction and the height direction, respectively, and the interval from the entrance ends of the input optical waveguides 23 to 25 is 10 μm.

Fig. 7 is an explanatory view of the propagation state of a red light beam in the optical multiplexer according to embodiment 2 of the present invention, fig. 7 (a) is a view of imaging the simulation result, and fig. 7 (b) is a view of copying fig. 7 (a). The red light beam entering the input optical waveguide 25 passes through the optical coupling section 47 with the coupling coefficient set to be small, and 85% of the incident power propagates through the input optical waveguide 25. A part of the red light beam moved to the input optical waveguide 24 is moved to the output optical waveguide 27 in the optical coupling section 48. The output from the output optical waveguide 27 was 3.2% of the incident power (the optical attenuation amount was 14.9 dB).

Fig. 8 is an explanatory view of the propagation state of a green light beam in the optical multiplexer according to embodiment 2 of the present invention, fig. 8 (a) is a view of imaging the simulation result, and fig. 8 (b) is a view of copying fig. 8 (a). The green light beam incident on the input optical waveguide 24 passes through the optical coupling sections 47 and 48 having a small coupling coefficient, and 94% of the incident power propagates through the input optical waveguide 24. The optical power that has moved to the output optical waveguide 27 in the optical coupling section 48 and is emitted from the output optical waveguide 27 is 3.0% of the incident power (the optical attenuation amount is 15.2 dB).

Fig. 9 is an explanatory view of the propagation state of the blue light beam in the optical multiplexer according to embodiment 2 of the present invention, fig. 9 (a) is a view obtained by imaging the simulation result, and fig. 9 (b) is a view copying fig. 9 (a). The blue light beam incident on the input optical waveguide 23 passes through the optical coupling section 46, and 96% of the incident power propagates through the input optical waveguide 23. The optical power that has moved to the output optical waveguide 27 in the optical coupling section 46 and has passed through the optical coupling section 48 and emitted from the output optical waveguide 27 is 2.5% of the incident power (the optical attenuation amount is 16.0 dB).

In embodiment 2 of the present invention, the length of the directional coupler constituting each optical coupling section can be reduced, and therefore, the optical multiplexer can be downsized.

Example 3

Next, an optical multiplexer according to embodiment 3 of the present invention will be described with reference to fig. 10, which is an optical multiplexer obtained by setting the incident end side of the input optical waveguide of the optical multiplexer according to embodiment 2 to be perpendicular to the output optical waveguide, and the basic configuration and operation principle thereof are the same as those of embodiment 2.

Fig. 10 is a plan view of a concept of an optical multiplexer according to embodiment 3 of the present invention, and here, a light source is illustrated as a light source module with a light source added for easy understanding of the present invention. As shown in fig. 10, the blue semiconductor laser chip 31 is disposed at one long side of the Si substrate, and the green semiconductor laser chip 32 and the red semiconductor laser chip 33 are disposed at the other long side of the Si substrate. Here, the intersection angle between the optical axis of each semiconductor laser and the central axis of the output optical waveguide 27 is 90 °. The crossing angle is arbitrary, but may be in the range of 85 ° to 95 ° in consideration of manufacturing error. Therefore, the input optical waveguides 23 to 25 are bent at right angles in the middle. A groove-structured total reflection mirror as shown in fig. 4 of patent document 3 is used for the right-angle bending, but a curved waveguide having a small radius of curvature may be used.

The outgoing light from the semiconductor laser is not completely coupled into the optical waveguide, and a part of the outgoing light propagates in the cladding layer as a fan-shaped beam. By adopting the structure shown in fig. 10, it is possible to suppress the fan-shaped light beam propagating through the cladding layer from mixing into the combined output light beam path, and thus it is possible to reduce the optical noise.

Example 4

Next, an optical multiplexer according to embodiment 4 of the present invention will be described with reference to fig. 11, which is an optical multiplexer obtained by bending the output end side of the input optical waveguide in embodiment 3 described above, and the basic configuration and operation principle thereof are the same as those in embodiment 3.

Fig. 11 is a plan view of a concept of an optical multiplexer according to embodiment 4 of the present invention, and here, a light source is illustrated as a light source module with a light source added for easy understanding of the present invention. As shown in fig. 11, the blue semiconductor laser chip 31 is disposed at one long side of the Si substrate, and the green semiconductor laser chip 32 and the red semiconductor laser chip 33 are disposed at the other long side of the Si substrate. The intersection angle between the optical axis of each semiconductor laser and the central axis of the output optical waveguide 27 of the optical multiplexer unit 45 is 90 °. The crossing angle is arbitrary, but may be in the range of 85 ° to 95 ° in consideration of manufacturing error. Therefore, the input optical waveguides 23 to 25 are bent at right angles in the middle. A groove-structured total reflection mirror as shown in fig. 4 of patent document 3 is used for the right-angle bending, but a curved waveguide having a small radius of curvature may be used.

In example 4 of the present invention, the output optical waveguide 27 was bent at the emission end side. Here, the bending angle is 90 °, but the bending angle is arbitrary, and may be in the range of 85 ° to 95 ° in consideration of manufacturing errors. In this case as well, a groove-structured total reflection mirror as shown in fig. 4 of patent document 3 is used to bend the output optical waveguide 27 at right angles, but a curved waveguide having a small radius of curvature may be used.

In this case as well, similarly to the structure shown in fig. 10, by adopting the structure of fig. 11, it is possible to suppress the fan-shaped light beam propagating through the cladding layer from being mixed into the combined output light beam path, and to reduce the optical noise. Further, the leaked light leaking from the optical coupling sections 46 to 48 of the optical multiplexer 45 does not overlap the multiplexed light emitted from the bent emission end of the output optical waveguide 27, and therefore the influence of noise light can be further reduced.

Example 5

Next, an optical multiplexer according to example 5 of the present invention will be described with reference to fig. 12, but the configuration of the light source is changed by changing the shape of the input optical waveguide for blue, and the configuration is otherwise the same as in example 3 described above. Fig. 12 is a plan view of a concept of an optical multiplexer according to embodiment 5 of the present invention, and here, a light source module is illustrated with a light source added for the convenience of understanding the present invention.

As shown in fig. 12, the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 are arranged at one long side of the Si substrate. The intersection angle between the optical axis of each semiconductor laser and the central axis of the output optical waveguide 27 is 90 °. The crossing angle is arbitrary, but may be in the range of 85 ° to 95 ° in consideration of manufacturing error. Therefore, the input optical waveguides 23 to 25 are bent at right angles in the middle. A groove-structured total reflection mirror as shown in fig. 4 of patent document 3 is used for the right-angle bending, but a curved waveguide having a small radius of curvature may be used.

In this case as well, by adopting the structure of fig. 12, as in the structure shown in fig. 10, it is possible to suppress the fan-shaped light beam propagating through the cladding layer from being mixed into the combined output light beam path, and thus it is possible to reduce optical noise. Further, since the light source is disposed at only one side, the dimension in the width direction (longitudinal direction in the drawing) can be reduced in the case where the light source module is formed. In example 5, the output optical waveguide 27 may be bent at the output end side as in example 4.

Example 6

Next, an optical multiplexer according to embodiment 6 of the present invention will be described with reference to fig. 13. Fig. 13 is a plan view of the concept of the optical multiplexer according to embodiment 6 of the present invention, and here, a light source is illustrated as a light source module with a light source added for easy understanding of the invention. The optical multiplexer 50 forms an optical multiplexer together with the input optical waveguides 23 to 25 and the output optical waveguide 27. The light emitted from the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 is not directly coupled to the output optical waveguide 27, and the combined light output is entirely transferred from the input optical waveguides 23 to 25 to the output optical waveguide 27 through the optical coupling sections 51 to 53.

The coupling coefficients of the optical coupling sections 51 to 53 are set to, for example, 3% for blue, green, and red light, respectively. The blue light that has moved to the output optical waveguide 27 in the optical coupling section 51 passes through the two optical coupling sections 52 and 53 before being emitted, but the coupling coefficient of the optical coupling sections 52 and 53 with respect to the blue light is less than 3%. Therefore, the amount of blue light that moves from the output optical waveguide 27 to the input optical waveguides 24 and 25 is 0.2% or less of the amount of incident light from the semiconductor laser. Similarly, the amount of green light that has moved to the output optical waveguide 27 in the optical coupling section 52 that has moved from the output optical waveguide 27 to the input optical waveguide 25 in the optical coupling section 53 is 0.1% or less. The optical multiplexer transmittance for blue, green, and red lights was 3% in all cases (the light attenuation was 15.2 dB).

In example 6 of the present invention, too, the light attenuation factor of the optical coupling section is set so that a desired display optical power can be obtained, and thus the light beam intensity can be attenuated to a desired value without providing an additional light attenuation element.

Example 7

Next, an optical multiplexer according to embodiment 7 of the present invention will be described with reference to fig. 14, which is an optical multiplexer obtained by bending the output end side of the output optical waveguide in embodiment 6 described above, and the basic configuration and operation principle thereof are the same as those in embodiment 6.

Fig. 14 is a plan view of the concept of the optical multiplexer according to embodiment 7 of the present invention, and here, a light source is illustrated as a light source module with a light source added for easy understanding of the present invention. The optical multiplexer 50 forms an optical multiplexer together with the input optical waveguides 23 to 25 and the output optical waveguide 27. The light emitted from the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 is not directly coupled to the output optical waveguide 27, and the combined light output is entirely transferred from the input optical waveguides 23 to 25 to the output optical waveguide 27 through the optical coupling sections 51 to 53.

In example 7 of the present invention, the output optical waveguide 27 was bent at the emission end side. Here, the bending angle is 90 °, but the bending angle is arbitrary, and may be in the range of 85 ° to 95 ° in consideration of manufacturing error. In this case as well, a groove-structured total reflection mirror as shown in fig. 4 of patent document 3 is used to bend the output optical waveguide 27 at right angles, but a curved waveguide having a small radius of curvature may be used.

In this case as well, by adopting the structure of fig. 14, as in the structure shown in fig. 11, it is possible to suppress the fan-shaped light beam propagating through the cladding layer from being mixed into the combined output light beam path, and it is possible to further reduce the influence of noise light because the leakage light of the optical coupling sections 51 to 53 of the optical combining section 50 does not overlap with the combined light emitted from the curved emission end of the output optical waveguide 27.

Example 8

Next, a light source module according to embodiment 8 of the present invention will be described with reference to fig. 15, but is completely the same as the light source module described with the light source added to the optical multiplexer in fig. 2 (a). Fig. 15 is a conceptual configuration diagram of an optical multiplexer according to embodiment 8 of the present invention. As shown in fig. 15, a light beam from the blue semiconductor laser chip 31 is input to the input optical waveguide 23, a light beam from the green semiconductor laser chip 32 is input to the input optical waveguide 24, and a light beam from the red semiconductor laser chip 33 is input to the input optical waveguide 25. The input optical waveguides 23 to 25 are connected to the optical waveguide of the optical multiplexer 40, and the combined light combined in the optical multiplexer 40 is output from the output end of the output optical waveguide 27.

The exit ports of the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 are installed so as to coincide with the entrance ports of the input optical waveguides 23 to 25 in the lateral direction and the height direction, respectively, and the interval from the entrance ends of the input optical waveguides 23 to 25 is 10 μm.

The structure of the optical multiplexer 40 is the same as that shown in fig. 2 (a), and the dimensions of the optical multiplexer 40 are 3mm in length and 3.1mm in width. The length of the optical coupling portion 41 is 350 μm, the length of the optical coupling portion 42 is 240 μm, the length of the optical coupling portion 43 is 200 μm, and the length of the optical coupling portion 44 is 1200 μm.

The structure of the optical multiplexer unit in the light source module is not limited to the optical multiplexer unit 40, and the optical multiplexer units 45 and 50 shown in embodiment 2 or embodiment 6 may be used. Further, the arrangement of the light sources is also arbitrary, and the arrangement shown in embodiment 3 or embodiment 5 may also be adopted. Further, the output optical waveguide may be bent at the output end side as shown in embodiment 4 or embodiment 7.

Example 9

Next, a light source module according to embodiment 9 of the present invention will be described with reference to fig. 16, which is a light source module according to embodiment 8 in which a lens is provided between a light source and an input optical waveguide. Fig. 16 is a conceptual configuration diagram of a light source module according to embodiment 9 of the present invention. As shown in fig. 16, a lens 36 is provided between the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33.

In this case, the lens 36 is, for example, a micro ball lens having a focal length of 0.54mm and a ball diameter of 1mm, and the light flux condensed by the micro ball lens is made incident on the input optical waveguides 23 to 25. The converging lens is not limited to a micro ball lens, and a GRIN (graded index type) lens may be used.

In this case, the structure of the optical multiplexer unit in the light source module is not limited to the optical multiplexer unit 40, and the optical multiplexer units 45 and 50 shown in embodiment 2 or embodiment 6 may be used. Further, the arrangement of the light sources is also arbitrary, and the arrangement shown in embodiment 3 or embodiment 5 may also be adopted. Further, as in embodiment 4 or embodiment 7, the output optical waveguide may be bent at the output end side.

Example 10

Next, a light source module according to example 10 of the present invention will be described with reference to fig. 17, and the same as example 8 is applied except that an optical fiber output end is used instead of the semiconductor laser as the light source in the light source module according to example 8. The emission wavelength of the red light beams at the exit ends of the optical fibers 37-39 is 640nm, the emission wavelength of the green light beams is 530nm, and the wavelength of the blue light beams is 450 nm.

In this case, the structure of the optical multiplexer unit in the light source module is not limited to the optical multiplexer unit 40, and the optical multiplexer units 45 and 50 shown in embodiment 2 or embodiment 6 may be used. Further, the arrangement of the light sources is also arbitrary, and the arrangement shown in embodiment 3 or embodiment 5 may also be adopted. Further, as in embodiment 4 or embodiment 7, the output optical waveguide may be bent at the output end side.

Example 11

Next, a light source module of example 11 of the present invention will be described with reference to fig. 18, and the same as example 8 except that a Light Emitting Diode (LED) is used as a light source in the light source module of example 8 instead of a semiconductor laser. That is, the basic operation principle is equivalent in that the light source module uses the blue LED chip 54 instead of the blue semiconductor laser chip 31, uses the green LED chip 55 instead of the green semiconductor laser chip 32, uses the red LED chip 56 instead of the red semiconductor laser chip 33, and slightly changes the sizes of the respective components in accordance with the use of the blue LED chip and the red semiconductor laser chip 33. The emission wavelength of the blue LED chip 54 is 540nm, the emission wavelength of the green LED chip 55 is 530nm, and the emission wavelength of the red LED chip 56 is 640 nm.

In this case, the structure of the optical multiplexer unit in the light source module is not limited to the optical multiplexer unit 40, and the optical multiplexer units 45 and 50 shown in embodiment 2 or embodiment 6 may be used. Further, the arrangement of the light sources is also arbitrary, and the arrangement shown in embodiment 3 or embodiment 5 may also be adopted. Further, as in example 4 or example 7, the output end side of the output optical waveguide may be bent, or as in example 9, a lens may be interposed.

Example 12

Next, a two-dimensional optical scanning device according to example 12 of the present invention will be described, but since only the structure of the optical multiplexer is different and the basic structure is the same as the two-dimensional optical scanning device shown in fig. 20, the description will be given with reference to fig. 20. The two-dimensional optical scanning device according to embodiment 12 of the present invention is obtained by replacing the optical multiplexer 62 in the two-dimensional optical scanning device of fig. 20 with the optical multiplexer shown in embodiment 1 described above. The optical multiplexer may be replaced with the optical multiplexer shown in embodiment 2 or embodiment 6. Further, the configuration of the light source may also be the configuration shown in embodiment 1 to embodiment 7. Further, as shown in fig. 16 to 18, a lens may be provided, or the light source may be replaced with an optical fiber or an LED.

Example 13

Next, an image forming apparatus according to example 13 of the present invention will be described with reference to fig. 21, but since the basic configuration is the same as that of the image forming apparatus shown in fig. 21, only the configuration of the optical multiplexer is different. The image forming apparatus according to embodiment 13 of the present invention is obtained by replacing the optical multiplexer 62 in the image forming apparatus of fig. 21 with the optical multiplexer shown in embodiment 1 described above. The optical multiplexer may be replaced with the optical multiplexer shown in embodiment 2 or embodiment 7. Further, the configuration of the light source may also be the configuration shown in embodiment 1 to embodiment 7. Further, as shown in fig. 16 to 18, a lens may be provided, or the light source may be replaced with an optical fiber or an LED.

In this image forming apparatus, the control unit 70 includes a control section 71, an operation section 72, an external interface (I/F)73, an R laser driver 74, a G laser driver 75, a B laser driver 76, and a two-dimensional scan driver 77, as in the conventional art. The control unit 71 is constituted by a microcomputer including a CPU, a ROM, and a RAM, for example. The control section 71 generates an R signal, a G signal, a B signal, a horizontal signal, and a vertical signal as elements for synthesizing an image from image data supplied from an external apparatus such as a PC via an external I/F73. The control unit 71 transmits the R signal to the R laser driver 74, the G signal to the G laser driver 75, and the B signal to the B laser driver 76. The control unit 71 sends a horizontal signal and a vertical signal to a two-dimensional scanning driver 77, and controls the current applied to the electromagnetic coil 64 to control the operation of the movable mirror portion 63.

The R laser driver 74 drives the red semiconductor laser chip 33 to generate red laser light of a light amount corresponding to the R signal from the control section 71. The G laser driver 75 drives the green semiconductor laser chip 32 to generate green laser light of a light amount corresponding to the G signal from the control section 71. The B laser driver 76 drives the blue semiconductor laser chip 31 to generate blue laser light of a light amount corresponding to the B signal from the control section 71. Laser light having a desired color can be synthesized by adjusting the intensity ratio of the laser light of each color.

The laser beams generated by the blue semiconductor laser chip 31, the green semiconductor laser chip 32, and the red semiconductor laser chip 33 are combined in the optical combining section (40) of the optical combiner, and then two-dimensionally scanned by the movable mirror section 63. The scanned combined laser light is reflected by the concave mirror 78 and is imaged on the retina 80 through the pupil 79.

Description of the reference symbols

1: a substrate; 2: an output optical waveguide; 3: an optical coupling section; 4: 1 st input optical waveguide; 5: a 2 nd input optical waveguide; 6: a 3 rd input optical waveguide; 7₁、7₂: 1 st optical coupling part; 8: a 2 nd optical coupling section; 9: an optical waste optical waveguide; 10: a 3 rd optical coupling section; 11₁、11₂、11₃: a light source; 12: a bending part; 21: a Si substrate; 22: a lower cladding layer; 23-25: an input optical waveguide; 26: an upper cladding layer; 27: an output optical waveguide; 28: an optical waste optical waveguide; 31: a blue semiconductor laser chip; 32: a green semiconductor laser chip; 33: a red semiconductor laser chip; 36: a lens; 37-39: an optical fiber; 40. 45, 50: a light wave combining unit; 41-44, 46-48, 51-53: an optical coupling section; 54: a blue LED chip; 55: a green LED chip; 56: a red LED chip; 61: substrate(ii) a 62: an optical multiplexer; 63: a movable mirror section; 64: an electromagnetic coil; 70: a control unit; 71: a control unit; 72: an operation section; 73: an external interface (I/F); 74: an R laser driver; 75: a G laser driver; 76: b, a laser driver; 77: a two-dimensional scan driver; 78: a concave reflector; 79: a pupil; 80: the retina.