JP7097332B2 - Combined demultiplexing element and light source module - Google Patents

Description

The present invention relates to a demultiplexing element and a light source module.

In recent years, the development of portable projectors, head-up displays (HUDs), head-mounted displays (HMDs), and the like has been accelerating, and there is a strong demand for ultra-miniaturization of scanning laser projection devices. As a main component of the scanning laser projection device, there is a combined wave module that combines the light output from each of the red light source, the green light source, and the blue light source, which are visible light sources. A light source module is configured to include a visible light source and a combined wave module.

As a combined wave module, there is one manufactured by using a space coupling technique such as a dichroic mirror. However, the space-coupled combined wave module requires extremely precise mounting of multiple components such as lenses, causes an increase in module size, and causes an increase in optical system loss due to misalignment during assembly. In some cases. Therefore, a Planar Lightwave Circuit (PLC) type combiner element composed of a quartz-based glass waveguide that can be manufactured by using a semiconductor process is attracting attention as a means that can solve the above-mentioned problems. (See Patent Documents 1 to 3).

Japanese Unexamined Patent Publication No. 2013-195603 JP-A-2019-355876 International Publication No. 2017/06525

Patent Documents 1 and 3 include two combiners for combining three visible lights of red light, green light, and blue light. However, it is difficult to reduce the size in a configuration including two combiners. In particular, since red light, green light, and blue light are separated in wavelength interval, the bond length becomes long when they are combined by using an interference action such as a directional coupler or a multimode interference type combiner. .. Therefore, since the length of the wave junction becomes long, it is more difficult to reduce the size. On the other hand, in Patent Document 2, since the output ports of the three waveguides are close to each other, high manufacturing accuracy such as the position and size of each waveguide is required. Therefore, it is difficult to manufacture, especially for microfabrication and waveguide spacing.

The present invention has been made in view of the above, and an object of the present invention is to provide a compact and easy-to-manufacture combined / demultiplexing element and a light source module.

In order to solve the above-mentioned problems and achieve the object, the combined demultiplexing element according to one aspect of the present invention includes a first waveguide to which the first visible light is input and the first visible light is waveguideed. A second visible light having a wavelength different from that of the first visible light is input, and a second waveguide for waveguideing the second visible light and a third visible light are input to waveguide the third visible light. The first waveguide, which is optically connected to the third waveguide, the fourth waveguide, the first waveguide, the second waveguide, and the fourth waveguide, is input from the first waveguide. A first duplexer that combines visible light with the second visible light input from the second waveguide and outputs it to the fourth waveguide is provided, and the third waveguide includes the first duplexer. The first output unit located on the side opposite to the side where the third visible light is input and the second output unit located on the side opposite to the side connected to the first duplexer in the fourth waveguide. The two output units are close to each other.

The third waveguide and the first duplexer may be arranged side by side in the width direction.

The first visible light may be red light, the second visible light may be blue light, and the third visible light may be green light.

The first visible light may be blue light, the second visible light may be green light, and the third visible light may be red light.

The first visible light may be red light, the second visible light may be green light, and the third visible light may be blue light.

The third visible light is input to the third waveguide, and the fifth waveguide for waveguideing the third visible light and the fourth visible light having a wavelength different from that of the third visible light are input. The sixth waveguide for waveguideing the fourth visible light, the third visible light input from the fifth waveguide, and the fourth visible light input from the sixth waveguide are combined and output. The first output unit is provided with a second duplexer and a seventh waveguide for waveguideing the third visible light and the fourth visible light output from the second duplexer. May be configured by the seventh waveguide.

The first waveguide, the second waveguide, the third waveguide, the fourth waveguide, and the first duplexer may include zirconia (ZrO ₂ ).

The light source module according to one aspect of the present invention is optically connected to the combined demultiplexing element and the first waveguide, and has the first visible light source that outputs the first visible light and the second guide. A second visible light source that is optically connected to the waveguide and outputs the second visible light and a third visible light source that is optically connected to the third waveguide and outputs the third visible light. And.

According to the present invention, there is an effect that a compact and easy-to-manufacture combined / demultiplexing element and a light source module can be realized.

FIG. 1 is a schematic configuration diagram of a light source module according to the first embodiment. FIG. 2 is a sectional view taken along line XX of FIG. FIG. 3 is a diagram showing an example of the relationship between the specific refractive index difference Δ and the core size. FIG. 4 is a schematic configuration diagram of the combined demultiplexing element according to the second embodiment. FIG. 5 is a schematic configuration diagram of the combined demultiplexing element according to the third embodiment. FIG. 6 is a diagram showing an example of the transmission characteristics of the combined demultiplexing element of Fabrication Example 1. FIG. 7 is a diagram showing another example of the transmission characteristics of the combined demultiplexing element of Fabrication Example 2. FIG. 8 is a schematic configuration diagram of the combined demultiplexing element according to the fourth embodiment.

Hereinafter, embodiments will be described with reference to the drawings. The present invention is not limited to this embodiment. Further, in the description of the drawings, the same or corresponding elements are appropriately designated by the same reference numerals. In addition, it should be noted that the drawings are schematic, and the relationship between the dimensions of each element, the ratio of each element, etc. may differ from the reality. Even between the drawings, there may be parts where the relationship and ratio of the dimensions are different from each other.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram of a light source module according to the first embodiment. The light source module 100 includes a combined demultiplexing element 10 and visible light sources 21, 22 and 23. The demultiplexing element 10 is made of a PLC made of quartz-based glass.

The combined demultiplexing element 10 includes a first waveguide 11a, a second waveguide 11b, a third waveguide 11c, a fourth waveguide 11d, a first waveguide demultiplexer 11e, and a clad 12. There is.

The clad 12 surrounds a first waveguide 11a, a second waveguide 11b, a third waveguide 11c, a fourth waveguide 11d, and a first duplexer 11e. FIG. 2 shows a state in which the clad 12 surrounds the first waveguide 11a, the second waveguide 11b, and the third waveguide 11c. The clad 12 includes a lower clad 12a located below each waveguide and an upper clad 12b located above and laterally of each waveguide. The clad 12 is formed on, for example, a silicon substrate or a glass substrate (not shown).

The demultiplexing element 10 has a first end portion 10a and a second end portion 10b facing the first end portion 10a in the longitudinal direction. The length of the demultiplexing element 10, that is, the distance between the first end portion 10a and the second end portion 10b is La. Further, the width of the combined demultiplexing element 10 is Wa.

The first demultiplexer 11e extends in the longitudinal direction. The first demultiplexer 11e has a known configuration, and has a structure including a waveguide, for example, a directional coupler type, a multimode interference type, and a Y-branch type.

The first waveguide 11a and the second waveguide 11b are bent and are optically connected to one end of the first waveguide 11e in the longitudinal direction. The ends of the first waveguide 11a and the second waveguide 11b on the opposite side of the end connected to the first duplexer 11e are extended to the first end 10a, respectively. The fourth waveguide 11d is bent and is optically connected to the other end in the longitudinal direction of the first duplexer 11e. The end of the fourth waveguide 11d opposite to the end connected to the first duplexer 11e extends to the second end 10b. The end portion of the fourth waveguide 11d on the second end portion 10b side is an output portion 11da as a second output portion. That is, the output unit 11da is located on the side opposite to the side connected to the first duplexer 11e in the fourth waveguide 11d.

The third waveguide 11c is bent and extends from the first end 10a to the second end 10b. The end portion of the third waveguide 11c on the second end portion 10b side is an output portion 11ca as a first output portion. The third waveguide 11c and the first duplexer 11e are aligned in the width direction.

The first waveguide 11a, the second waveguide 11b, the third waveguide 11c, the fourth waveguide 11d, and the first duplexer 11e are quartz-based glasses containing zirconia (ZrO ₂ ), which is a dopant that increases the refractive index. Consists of. On the other hand, the clad 12 is made of, for example, pure quartz glass. Here, the pure quartz glass is defined to include a quartz glass containing no impurities and a quartz glass containing impurities but not containing impurities that change the refractive index of the quartz glass. The specific refractive index difference Δ with respect to the clad 12 of the first waveguide 11a, the second waveguide 11b, the third waveguide 11c, the fourth waveguide 11d, and the first duplexer 11e is not particularly limited, but in the present embodiment. It is 0.45%, and a high specific refractive index difference can be realized at a lower concentration than when using a waveguide using germania (GeO ₂ ).

The first waveguide 11a, the second waveguide 11b, the third waveguide 11c, the fourth waveguide 11d, and the first waveguide 11e are provided under the condition that visible light having a predetermined wavelength is guided in a single mode. The relationship between the cross-sectional size and the specific refractive index difference Δ is set. However, the relationship between the cross-sectional size and the specific refractive index difference Δ may be set to a condition in which visible light having a predetermined wavelength is guided in a multi-mode.

FIG. 3 is a diagram showing an example of the relationship between the specific refractive index difference Δ and the core size. The core size is the length of one side of a square when the cross-sectional shape in the cross section perpendicular to the longitudinal direction of the waveguide is a square. The core size indicates a value that can guide light of wavelength λ in a single mode. As the wavelength λ, the case of 1550 nm used in communication and the case of 460 nm, which is a relatively short wave in the visible light region, are shown. As shown in FIG. 3, it is necessary to significantly reduce the core size in the case of 460 nm as compared with the case of 1550 nm. For example, when the specific refractive index difference Δ is 0.45%, the core size is 7.5 μm on a side at a wavelength of 1550 nm, and 3 μm on a side at a wavelength of 460 nm. FIG. 3 shows the case of single-mode waveguide, but the wavelength dependence of the core size shows the same tendency in the case of multi-mode waveguide.

Returning to FIG. 1, the visible light source 21 is optically connected to the first waveguide 11a, and outputs red light L1 as the first visible light to the first waveguide 11a. The visible light source 22 is optically connected to the second waveguide 11b, and outputs blue light L2 as the second visible light having a wavelength different from that of the first visible light to the second waveguide 11b. The visible light source 23 is optically connected to the third waveguide 11c, and outputs green light L3 as the third visible light to the third waveguide 11c. The visible light sources 21, 22, and 23 may be butt-joint connected to the demultiplexing element 10.

In the present embodiment, the first waveguide 11a has a configuration in which the red light L1 is input from the first end portion 10a side and the red light L1 is guided in a single mode. The wavelength of the red light L1 is, for example, 620 nm to 750 nm. The second waveguide 11b has a configuration in which the blue light L2 is input from the first end portion 10a side and the blue light L2 is guided in a single mode. The wavelength of the blue light L2 is, for example, 450 nm to 495 nm. The first duplexer 11e combines the red light L1 input from the first waveguide 11a and the blue light L2 input from the second waveguide 11b and outputs the combined waves to the fourth waveguide 11d. The fourth waveguide 11d waveguides the input red light L1 and blue light L2 and outputs them from the output unit 11da. Due to the reciprocity of light, the first demultiplexer 11e has a demultiplexing function and a demultiplexing function of light.

The third waveguide 11c has a configuration in which the green light L3 is input from the first end portion 10a side, the green light L3 is guided in a single mode, and is output from the output unit 11ca. The wavelength of the green light L3 is, for example, 495 nm to 570 nm. That is, the output unit 11ca is located on the third waveguide 11c on the side opposite to the side on which the green light L3 is input.

Here, the output unit 11ca and the output unit 11da are close to each other. As a result, the combined demultiplexing element 10 outputs the red light L1, the blue light L2, and the green light L3 as RGB light L4 that can be regarded as one beam. The distance between the output unit 11ca and the output unit 11da in the second end portion 10b, that is, the length of the clad 12 between the output unit 11ca and the output unit 11da is, for example, 10 μm or less. Further, the length of the clad 12 is, for example, 2.5 μm or more.

The light source module 100 includes a combined / demultiplexing element 10, and the combined / demultiplexing element 10 includes one first demultiplexer 11e as a demultiplexer, and has red light L1, blue light L2, and green light. The three visible lights of L3 are output as RGB light L4. As a result, the demultiplexing element 10 and the light source module 100 are small and short, especially in the longitudinal direction. Further, when the visible light sources 21, 22, and 23 that output the red light L1, the blue light L2, and the green light L3 are semiconductor laser elements or the like, the oscillation wavelength varies due to the manufacturing process. Therefore, in the wavelength band of light of each color, for example, a wide band combined demultiplexing characteristic (for example, transmission characteristic) of ± 10 nm is strongly required. In the combined demultiplexing element 10, since there is only one combined demultiplexer, a certain band can be secured even if the transmission characteristic fluctuates due to the size fluctuating from the design value in the manufacturing process. That is, the combined demultiplexing element 10 can stably realize a wide band. When the combine / demultiplexing element has a configuration in which a plurality of combiners are connected, fluctuations from the design value of each combiner / demultiplexer are interlocked and the transmission characteristics greatly fluctuate, which causes an increase in loss. There is a risk that it will end up.

When a multi-mode interference type demultiplexer with 2 inputs x 2 outputs is used as the first demultiplexer 11e, the demultiplexing element 10 can have a length La x width Wa of, for example, 6.5 mm x 0.5 mm. .. The same size can be obtained when another type such as a directional coupler type is used as the first demultiplexer 11e.

Further, the combined demultiplexing element 10 has three visible lights of red light L1, blue light L2, and green light L3 by bringing the two waveguides of the third waveguide 11c and the fourth waveguide 11d close to each other. Is output as RGB light L4. As a result, the combined demultiplexing element 10 is easy to manufacture because the requirement for manufacturing accuracy such as the position and size of each waveguide is reduced as compared with the configuration in which the three waveguides are brought close to each other. Further, although the output RGB light L4 has an elliptical beam shape, the reduction in the number of waveguides in close proximity reduces individual differences in the core shape and beam shape of the combined demultiplexing element 10, resulting in a stable beam. The shape is obtained.

When the visible light sources 21, 22, and 23 that output the red light L1, the blue light L2, and the green light L3 are semiconductor laser elements, the visible light source 23, which is a green laser light source, is a red laser light source or a blue laser light source. The output may be lower than certain visible light sources 21 and 22. On the other hand, in the combine / demultiplexing element 10, the green light L3 does not pass through the first demultiplexer 11e and is output without receiving the excessive loss of the first demultiplexer 11e. As a result, the combined demultiplexing element 10 can reduce the intensity difference between the input green light L3 and the red light L1 and the blue light L2.

(Embodiment 2)
FIG. 4 is a schematic configuration diagram of the combined demultiplexing element according to the second embodiment. The combined demultiplexing element 10A is made of a PLC made of quartz-based glass, as in the first embodiment.

The combined demultiplexing element 10A includes a first waveguide 11Aa, a second waveguide 11Ab, a third waveguide 11Ac, a fourth waveguide 11Ad, a first waveguide demultiplexer 11Ae, and a clad 12A. There is.

The clad 12A surrounds a first waveguide 11Aa, a second waveguide 11Ab, a third waveguide 11Ac, a fourth waveguide 11Ad, and a first duplexer 11Ae. The clad 12A has the same configuration as the clad 12 of the first embodiment.

The demultiplexing element 10A has a first end portion 10Aa and a second end portion 10Ab facing the first end portion 10Aa in the longitudinal direction. The first demultiplexer 11Ae extends in the longitudinal direction. The first demultiplexer 11Ae has a known configuration as in the first demultiplexer 11e of the first embodiment.

The first waveguide 11Aa and the second waveguide 11Ab are bent and are optically connected to one end of the first waveguide 11Ae in the longitudinal direction. The ends of the first waveguide 11Aa and the second waveguide 11Ab on the opposite side of the end connected to the first duplexer 11Ae extend to the first end 10Aa, respectively. The fourth waveguide 11Ad is optically connected to the other end in the longitudinal direction of the first duplexer 11Ae. The end of the 4th waveguide 11Ad opposite to the end connected to the 1st demultiplexer 11Ae extends to the 2nd end 10Ab. The end portion of the fourth waveguide 11Ad on the second end portion 10Ab side is an output portion 11Ada as a second output portion.

The third waveguide 11Ac is bent and extends from the first end 10Aa to the second end 10Ab. The end portion of the third waveguide 11Ac on the second end portion 10Ab side is an output portion 11Aca as a first output portion. The third waveguide 11Ac and the first duplexer 11Ae are aligned in the width direction.

The first waveguide 11Aa, the second waveguide 11Ab, the third waveguide 11Ac, the fourth waveguide 11Ad and the first waveguide demultiplexer 11Ae are made of quartz-based glass containing zirconia. The specific refractive index difference Δ of the first waveguide 11Aa, the second waveguide 11Ab, the third waveguide 11Ac, the fourth waveguide 11Ad, and the first duplexer 11Ae with respect to the clad 12A is not particularly limited.

The first waveguide 11Aa, the second waveguide 11Ab, the third waveguide 11Ac, the fourth waveguide 11Ad, and the first waveguide 11Ae are provided under the condition that visible light having a predetermined wavelength is guided in a single mode. Although the relationship between the cross-sectional size and the specific refractive index difference Δ is set, it may be set under the condition of waveguide in multimode.

In the present embodiment, the first waveguide 11Aa has a configuration in which blue light L2 as the first visible light is input from the first end portion 10Aa side and the blue light L2 is guided in a single mode. The second waveguide 11Ab has a configuration in which the green light L3 as the second visible light is input from the first end portion 10Aa side and the green light L3 is guided in a single mode. The first duplexer 11Ae combines the blue light L2 input from the first waveguide 11Aa and the green light L3 input from the second waveguide 11Ab and outputs the combined waves to the fourth waveguide 11Ad. The fourth waveguide 11Ad waveguides the input blue light L2 and green light L3 and outputs them from the output unit 11Ada.

The third waveguide 11Ac has a configuration in which red light L1 as the third visible light is input from the first end portion 10Aa side, the red light L1 is waveguideed in a single mode, and is output from the output unit 11Aca.

Here, the output unit 11Aca and the output unit 11Ada are in close proximity to each other. As a result, the combined demultiplexing element 10A outputs the red light L1, the blue light L2, and the green light L3 as RGB light L5 which can be regarded as one beam. The distance between the output unit 11Aca and the output unit 11Ada in the second end portion 10Ab is, for example, 10 μm or less.

The combined demultiplexing element 10A includes one first demultiplexing device 11Ae as a demultiplexing device, and outputs three visible lights of red light L1, blue light L2, and green light L3 as RGB light L5. As a result, as in the first embodiment, the combined demultiplexing element 10 is small in size, particularly short in the longitudinal direction, and can realize a stable wide band. Further, the combined demultiplexing element 10A has two waveguides, the third waveguide 11Ac and the fourth waveguide 11Ad, in close proximity to each other. As a result, as in the first embodiment, the combined demultiplexing element 10 is easy to manufacture, and individual differences in the core shape and the beam shape are reduced.

Further, in general, the bending loss of the waveguide increases as the wavelength becomes longer, so that the red light L1 has the largest bending loss among the red light L1, the blue light L2, and the green light L3. On the other hand, in the combined demultiplexing element 10A, the red light L1 is guided through a third waveguide 11Ac extending from the first end portion 10Aa to the second end portion 10Ab. As a result, in the combined demultiplexing element 10A, a wide space can be allocated in the longitudinal direction with respect to the third waveguide 11Ac, and the bending radius can be designed to be relatively large. As a result, in the combined demultiplexing element 10A, the bending loss of the red light L1 is reduced.

It should be noted that the combined demultiplexing element 10A and the visible light sources 21, 22 and 23 of the first embodiment can be combined to form a small light source module.

(Embodiment 3)
FIG. 5 is a schematic configuration diagram of the combined demultiplexing element according to the third embodiment. The combined demultiplexing element 10B is made of a PLC made of quartz-based glass, as in the first embodiment.

The combined demultiplexing element 10B includes a first waveguide 11Ba, a second waveguide 11Bb, a third waveguide 11Bc, a fourth waveguide 11Bd, a first waveguide demultiplexer 11Be, and a clad 12B. There is.

The clad 12B surrounds a first waveguide 11Ba, a second waveguide 11Bb, a third waveguide 11Bc, a fourth waveguide 11Bd, and a first duplexer 11Be. The clad 12B has the same configuration as the clad 12 of the first embodiment.

The demultiplexing element 10B has a first end portion 10Ba and a second end portion 10Bb facing the first end portion 10Ba in the longitudinal direction. The first demultiplexer 11Be extends in the longitudinal direction. The first demultiplexer 11Be has a known configuration as in the first demultiplexer 11e of the first embodiment.

The first waveguide 11Ba and the second waveguide 11Bb are bent and are optically connected to one end of the first waveguide 11Be in the longitudinal direction. The ends of the first waveguide 11Ba and the second waveguide 11Bb on the opposite side of the end connected to the first duplexer 11Be extend to the first end 10Ba, respectively. The fourth waveguide 11Bd is optically connected to the other end in the longitudinal direction of the first duplexer 11Be. The end of the fourth waveguide 11Bd opposite to the end connected to the first duplexer 11Be extends to the second end 10Bb. The end portion of the fourth waveguide 11Bd on the second end portion 10Bb side is an output portion 11Bda as a second output portion.

The third waveguide 11Bc is bent and extends from the first end 10Ba to the second end 10Bb. The end portion of the third waveguide 11Bc on the second end portion 10Bb side is an output portion 11Bca as a first output portion. The third waveguide 11Bc and the first duplexer 11Be are arranged in the width direction.

The first waveguide 11Ba, the second waveguide 11Bb, the third waveguide 11Bc, the fourth waveguide 11Bd, and the first duplexer 11Be are made of quartz-based glass containing zirconia. The specific refractive index difference Δ of the first waveguide 11Ba, the second waveguide 11Bb, the third waveguide 11Bc, the fourth waveguide 11Bd, and the first duplexer 11Be with respect to the clad 12B is not particularly limited.

The first waveguide 11Ba, the second waveguide 11Bb, the third waveguide 11Bc, the fourth waveguide 11Bd, and the first waveguide 11Be are provided under the condition that visible light having a predetermined wavelength is guided in a single mode. Although the relationship between the cross-sectional size and the specific refractive index difference Δ is set, it may be set under the condition of waveguide in multimode.

In the present embodiment, the first waveguide 11Ba has a configuration in which red light L1 as the first visible light is input from the first end portion 10Ba side and the red light L1 is guided in a single mode. The second waveguide 11Bb has a configuration in which the green light L3 as the second visible light is input from the first end portion 10Ba side and the green light L3 is guided in a single mode. The first duplexer 11Be combines the red light L1 input from the first waveguide 11Ba and the green light L3 input from the second waveguide 11Bb and outputs the combined waves to the fourth waveguide 11Bd. The fourth waveguide 11Bd waveguides the input red light L1 and green light L3 and outputs them from the output unit 11Bda.

The third waveguide 11Bc has a configuration in which blue light L2 as the third visible light is input from the first end portion 10Ba side, the blue light L2 is waveguideed in a single mode, and is output from the output unit 11Bca.

Here, the output unit 11Bca and the output unit 11Bda are close to each other. As a result, the combined demultiplexing element 10B outputs the red light L1, the blue light L2, and the green light L3 as RGB light L6 that can be regarded as one beam. The distance between the output unit 11Bca and the output unit 11Bda in the second end portion 10Bb is, for example, 10 μm or less.

The combined demultiplexing element 10B includes one first demultiplexing device 11Be as a demultiplexing device, and outputs three visible lights of red light L1, blue light L2, and green light L3 as RGB light L6. As a result, as in the first embodiment, the combined demultiplexing element 10B is small in size, particularly short in the longitudinal direction, and can realize a stable wide band. Further, the combined demultiplexing element 10B has two waveguides, the third waveguide 11Bc and the fourth waveguide 11Bd, in close proximity to each other. As a result, as in the first embodiment, the combined demultiplexing element 10B is easy to manufacture, and individual differences in the core shape and the beam shape are reduced.

Also, in general, the bond length in the combiner becomes longer as the wavelength becomes shorter. On the other hand, in the combined demultiplexing element 10B, the red light L1 and the green light L3 having a relatively long wavelength are combined by the first demultiplexer 11Be. As a result, the first demultiplexer 11Be becomes relatively short, so that the demultiplexing element 10A becomes even smaller.

It should be noted that the combined demultiplexing element 10B and the visible light sources 21, 22 and 23 of the first embodiment can be combined to form a small light source module.

Hereinafter, simulation calculation results using the Beam Propagation Method (BPM) and an example thereof will be described.

First, as an example of comparative calculation, the size of a rectangular multimode interference type duplexer in a plan view was calculated. The specific refractive index difference Δ was 0.45%. The core size of the first, second, and fourth waveguides was 3 μm × 3 μm. The width of the duplexer was 6 μm. As a result, in the design of combining blue light having a wavelength of 465 nm and red light having a wavelength of 630 nm, the length of the duplexer was 4.5 mm. Further, in the design of combining the blue light having a wavelength of 465 nm, the red light having a wavelength of 630 nm, and the green light having a wavelength of 520 nm, the length of the duplexer was 10 mm. Therefore, when a combined demultiplexing element is manufactured using these two combined demultiplexers, it is considered that the length exceeds 20 mm.

Subsequently, as a calculation example 1, the size of the combined demultiplexing element 10 according to the first embodiment was calculated. The first demultiplexer 11e is a directional coupler type. Then, based on the calculation result, as Production Example 1, a combined demultiplexing element was produced using a known PLC production technique. The specific refractive index difference Δ was 0.45%. The core size of the first to fourth waveguides was 3 μm × 3 μm. The minimum bending radius of the first waveguide 11a and the second waveguide 11b was 5.0 mm. The minimum bending radius of the third waveguide 11c was 5.0 mm. As a result, the size of the demultiplexing element was as small as 5.0 mm × 0.5 mm.

FIG. 6 is a diagram showing the transmission characteristics of the combined demultiplexing element of Production Example 1. The region R1 indicates a blue region of ± 10 nm centered on the wavelength of 465 nm indicated by the arrow. The region R2 shows a green region of ± 10 nm centered on the wavelength 520 nm indicated by the arrow. The region R3 shows a red region of ± 10 nm centered on the wavelength of 630 nm indicated by the arrow. R → C in the legend shows the transmission characteristics of the first waveguide (11a in FIG. 1) to the fourth waveguide (11d in FIG. 1). B → C in the legend show the transmission characteristics from the first waveguide (11a in FIG. 1) to the fourth waveguide (11d in FIG. 1). G → C in the legend shows the transmission characteristics of the third waveguide (11c in FIG. 1).

In the combined demultiplexing element of Production Example 1, the light loss is 0.1 dB to 0.4 dB in the blue region of the region R1, 0.05 dB to 0.2 dB in the green region of the region R2, and 0. It was 3 dB to 0.9 dB, which was a practically preferable value.

Subsequently, as Calculation Example 2, the size of the combined demultiplexing element 10A according to the second embodiment was calculated. The first demultiplexer 11Ae was a directional coupler type. Then, based on the calculation result, as Production Example 2, a combined demultiplexing element was produced using a known PLC production technique. The difference in specific refractive index Δ was 0.45%. The core size of the first to fourth waveguides was 3 μm × 3 μm. The minimum bending radius of the first waveguide 11Aa and the second waveguide 11Ab was set to 2.0 mm. The minimum bending radius of the third waveguide 11Ac was 5.0 mm. As a result, the size of the demultiplexing element was as small as 4.5 mm × 0.5 mm.

FIG. 7 is a diagram showing the transmission characteristics of the combined demultiplexing element of Production Example 2. The area R1, the area R2, and the area R3 are the same as those in FIG. R → C in the legend shows the transmission characteristics of the third waveguide (11Ac in FIG. 4). B → C in the legend show the transmission characteristics from the first waveguide (11a in FIG. 4) to the fourth waveguide (11Ad in FIG. 4). G → C in the legend shows the transmission characteristics from the second waveguide (11Ab in FIG. 1) to the fourth waveguide.

In the combined demultiplexing element of Production Example 2, the light loss is 0.1 dB to 0.5 dB in the blue region of the region R1, 0.2 dB to 0.8 dB in the green region of the region R2, and 0. It was 05 dB to 0.2 dB, which was a practically preferable value.

(Embodiment 4)
In the above embodiment, three visible lights are combined, but the present invention can also be applied to a case where four or more visible lights are combined.

FIG. 8 is a schematic configuration diagram of the combined demultiplexing element according to the fourth embodiment. The combined demultiplexing element 10C is made of a PLC made of quartz-based glass, as in the first embodiment.

The combined demultiplexing element 10C includes a first waveguide 11Ca, a second waveguide 11Cb, a third waveguide 11Cc, a fourth waveguide 11Cd, a first waveguide demultiplexer 11Ce, and a clad 12C. There is.

The clad 12C surrounds a first waveguide 11Ca, a second waveguide 11Cb, a third waveguide 11Cc, a fourth waveguide 11Cd, and a first duplexer 11Ce. The clad 12C has the same configuration as the clad 12 of the first embodiment.

The demultiplexing element 10C has a first end portion 10Ca and a second end portion 10Cb facing the first end portion 10Ca in the longitudinal direction. The first demultiplexer 11Ce extends in the longitudinal direction. The first demultiplexer 11Ce has a known configuration as in the first demultiplexer 11e of the first embodiment.

The first waveguide 11Ca and the second waveguide 11Cb are bent and are optically connected to one end of the first waveguide 11Ce in the longitudinal direction. The ends of the first waveguide 11Ca and the second waveguide 11Cb on the opposite side of the end connected to the first duplexer 11Ce extend to the first end 10Ca, respectively. The fourth waveguide 11Cd is optically connected to the other end in the longitudinal direction of the first duplexer 11Ce. The end of the 4th waveguide 11Cd opposite to the end connected to the 1st demultiplexer 11Ce extends to the 2nd end 10Cb. The end portion of the fourth waveguide 11Cd on the second end portion 10Cb side is an output portion 11Cda as a second output portion.

The third waveguide 11Cc is bent and extends from the first end 10Ca to the second end 10Cb. The end of the third waveguide 11Cc on the second end 10Cb side is an output section 11Cca as a first output section. The third waveguide 11Cc and the first duplexer 11Ce are aligned in the width direction.

The third waveguide 11Cc includes a fifth waveguide 11Cc1, a sixth waveguide 11Cc2, a second waveguide 11Cc3, and a seventh waveguide 11Cc4. One end of the fifth waveguide 11Cc1 and the sixth waveguide 11Cc2 extends to the first end 10Ca side, and the other end is optically connected to the second duplexer 11Cc3. One end of the seventh waveguide 11Cc4 extends to the second end 10Cb side, and the other end is optically connected to the second duplexer 11Cc3. The seventh waveguide 11Cc4 constitutes the output unit 11Cca. The second demultiplexer 11Cc3 extends in the longitudinal direction. The second demultiplexer 11Cc3 has a known configuration, and has a structure including a waveguide, for example, a directional coupler type, a multimode interference type, and a Y-branch type.

The first waveguide 11Ca, the second waveguide 11Cb, the third waveguide 11Cc, the fourth waveguide 11Cd, and the first duplexer 11Ce are made of quartz-based glass containing zirconia. The specific refractive index difference Δ of the first waveguide 11Ca, the second waveguide 11Cb, the third waveguide 11Cc, the fourth waveguide 11Cd, and the first duplexer 11Ce with respect to the clad 12C is not particularly limited.

The first waveguide 11Ca, the second waveguide 11Cb, the third waveguide 11Cc, the fourth waveguide 11Cd, and the first waveguide 11Be are provided under the condition that visible light having a predetermined wavelength is guided in a single mode. Although the relationship between the cross-sectional size and the specific refractive index difference Δ is set, it may be set under the condition of waveguide in multimode.

In the present embodiment, the first waveguide 11Ca has a configuration in which red light L1 as the first visible light is input from the first end portion 10Ca side and the red light L1 is guided in a single mode. The second waveguide 11Cb has a configuration in which green light L3a as the second visible light is input from the first end portion 10Ba side and the green light L3a is guided in a single mode. The first duplexer 11Ce combines the red light L1 input from the first waveguide 11Ca and the green light L3a input from the second waveguide 11Cb and outputs the combined waves to the fourth waveguide 11Cd. The fourth waveguide 11Cd waveguides the input red light L1 and green light L3a and outputs the input from the output unit 11Cda.

On the other hand, in the third waveguide 11Cc, the fifth waveguide 11Cc1 has a configuration in which blue light L2 as the third visible light is input from the first end portion 10Ca side and the blue light L2 is guided in a single mode. The sixth waveguide 11Cc2 has a configuration in which green light L3b as the fourth visible light having a wavelength different from that of the third visible light is input from the first end portion 10Ca side and the green light L3b is waveguideed in a single mode. The second duplexer 11Cc3 combines the blue light L2 input from the fifth waveguide 11Cc1 and the green light L3b input from the sixth waveguide 11Cc2 and outputs the combined waves to the seventh waveguide 11Cc4. The seventh waveguide 11Cc4 guides the input blue light L2 and the green light L3b and outputs them from the output unit 11Cca.

Here, the output unit 11Cca and the output unit 11Cda are close to each other. As a result, the combined demultiplexing element 10C outputs four visible lights of red light L1, blue light L2, and green light L3a and L3b as RGB light L7 which can be regarded as one beam. The distance between the output unit 11Cca and the output unit 11Cda at the second end portion 10Cb is, for example, 10 μm or less.

The combined demultiplexing element 10C includes two first demultiplexers 11Ce and a second demultiplexer 11Cc3 as a demultiplexer, and has four red light L1, blue light L2, and green light L3a and L3b. Two visible lights are output as RGB light L7. As a result, as in the first embodiment, the combined demultiplexing element 10B is small in size, particularly short in the longitudinal direction, and can realize a stable wide band. Further, the combined demultiplexing element 10C has two waveguides, the third waveguide 11Cc and the fourth waveguide 11Cd, in close proximity to each other. As a result, as in the first embodiment, the combined demultiplexing element 10B is easy to manufacture, and individual differences in the core shape and the beam shape are reduced.

Further, when the light source that outputs the red light L1, the blue light L2, and the green light L3 is a semiconductor laser element, the output of the green laser light source may be lower than that of the red laser light source or the blue laser light source. On the other hand, in the combined demultiplexing element 10C, green light L3a and L3b can be input as green light. As a result, the combined demultiplexing element 10 can reduce the intensity difference between the total intensity of the input green light L3a and the green light L3b and the red light L1 and the blue light L2.

Further, the combined demultiplexing element 10C, the visible light sources 21 and 22 of the first embodiment, and the two visible light sources 23 can be combined to form a small light source module.

In the present embodiment, the fourth visible light is green light, but the fourth visible light may be visible light having other wavelengths such as blue light, red light, or other colors. Further, the wavelengths of the first to third visible light may be visible light having other wavelengths.

Furthermore, when combining 5 or more visible lights, the combiner / demultiplexer, which is one or more less than the number of visible lights, and the output unit, which is one or more less than the number of visible lights, are brought close to each other. , The combined demultiplexing element according to the embodiment of the present invention can be configured.

Further, in the above embodiment, each waveguide contains zirconia, but Germania may be contained. The miniaturization and ease of manufacture of the demultiplexing element can be realized regardless of the dopant that increases the refractive index.

Further, the present invention is not limited to the above embodiments. The present invention also includes a configuration in which the above-mentioned components are appropriately combined. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above embodiment, and various modifications can be made.

10, 10A, 10B, 10C Combined demultiplexing element 10a, 10Aa, 10Ba, 10Ca 1st end 10b, 10Bb, 10Cb 2nd end 11a, 11Aa, 11Ba, 11Ca 1st waveguide 11b, 11Ab, 11Bb, 11Cb 2 Waveguides 11c, 11Ac, 11Bc, 11Cc 3rd Waveguide 11ca, 11da, 11Aca, 11Ada, 11Bca, 11Bda, 11Cca, 11Cda Output Units 11d, 11Ad, 11Bd, 11Cd 4th Waveguide 11e, 11Ae, 11Be, 11Ce No. 1 Waveguide 11Cc1 5th Waveguide 11Cc2 6th Waveguide 11Cc3 2nd Waveguide 11Cc4 7th Waveguide 12, 12A, 12B, 12C Clad 12a Lower Clad 12b Upper Clad 21, 22, 23 Visible Light 100 Light Source Module L1 Red light L2 Blue light L3, L3a, L3b Green light L4, L5, L6, L7 RGB light R1, R2, R3 region

Claims (7)

A first waveguide to which the first visible light is input and waveguides to the first visible light,
A second waveguide in which a second visible light having a wavelength different from that of the first visible light is input and the second visible light is guided,
A third waveguide to which a third visible light is input and waveguides to the third visible light,
With the 4th waveguide
Optically connected to the first waveguide, the second waveguide, and the fourth waveguide, the first visible light input from the first waveguide and the second visible light input from the second waveguide. A first duplexer that combines the second visible light and outputs it to the fourth waveguide.
Equipped with
In the third waveguide, the first output unit located on the side opposite to the side where the third visible light is input, and the side connected to the first duplexer in the fourth waveguide. Is close to the second output section located on the opposite side to the distance of 2.5 μm or more and 10 μm or less .
The third waveguide is
A fifth waveguide to which the third visible light is input and waveguides to the third visible light,
A sixth waveguide in which a fourth visible light having a wavelength different from that of the third visible light is input and the fourth visible light is guided.
A second demultiplexer that combines and outputs the third visible light input from the fifth waveguide and the fourth visible light input from the sixth waveguide, and
A seventh waveguide that guides the third visible light and the fourth visible light output from the second duplexer, and
Equipped with
The first output unit is composed of the seventh waveguide.
The wavelength of the fourth visible light is the same as the wavelength of the first visible light or the wavelength of the second visible light.
A demultiplexing element characterized by this. The combined demultiplexing element according to claim 1, wherein the third waveguide and the first demultiplexer are arranged side by side in the width direction. The combined demultiplexing element according to claim 1 or 2, wherein the first visible light is red light, the second visible light is blue light, and the third visible light is green light. The combined demultiplexing element according to claim 1 or 2, wherein the first visible light is blue light, the second visible light is green light, and the third visible light is red light. The combined demultiplexing element according to claim 1 or 2, wherein the first visible light is red light, the second visible light is green light, and the third visible light is blue light. Claims 1 to 5 , wherein the first waveguide, the second waveguide, the third waveguide, the fourth waveguide, and the first waveguide include zirconia (ZrO ₂ ). The combined waveguide element according to any one of the above. The combined / demultiplexing element according to any one of claims 1 to 6 .
A first visible light source that is optically connected to the first waveguide and outputs the first visible light,
A second visible light source that is optically connected to the second waveguide and outputs the second visible light,
A third visible light source that is optically connected to the third waveguide and outputs the third visible light,
A light source module characterized by being equipped with.

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