JP3193793B2 - Waveguide-type photodetector and guided-light detection method thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a waveguide type photodetector in an integrated optical waveguide device and a method for detecting the guided light.

[0002]

2. Description of the Related Art Various proposals have been made for conventional waveguide type photodetectors in order to improve the light use efficiency. For example, a photodetector is provided in a slab type waveguide, an optical deflector is disposed in front of the photodetector, and the amount of deflection of the guided light by the optical deflector is detected as a difference in the amount of received light to the photodetector. Alternatively, there is a method in which the light deflector is further provided with a light-condensing function so that the deflected light is condensed on the photodetector to improve the detection sensitivity.

FIG. 10A shows a specific configuration example of a waveguide type photodetector having the slab type waveguide. The buffer layer 2 for reducing the absorption of the guided light a by the substrate 1 is formed on the substrate 1, and the optical waveguide layer 3 for guiding the guided light a is laminated on the buffer layer 2. . On the upper surface of the substrate 1, a photodetector 4 for detecting the guided light a in the optical waveguide layer 3 is provided.

In this case, in order to improve the light detection efficiency of the photodetector 4, the waveguide layer inclined portion 5 is formed by gradually attenuating the thickness of the buffer layer 2 from the front of the waveguide light incident side. , The buffer layer 2 on the surface of the photodetector 4 is formed as thin as possible. As a result, as shown in FIG.
Is received by the photodetector 4 using the waveguide layer inclined part 5,
The light detection can be performed by sending the received signal to an external control circuit (not shown) via the electrode 6.

As a means for further improving the light use efficiency as compared with the above-described example, as shown in FIGS. 11A to 11C, an optical coupler for coupling external light b to the optical waveguide layer 3 is used. 7 and light collectors 8a and 8b provided in the optical waveguide layer 3.
And the like can be realized by integrally forming them. FIG. 11A shows a case where the external light b is parallel light incident.
FIG. 11B shows the respective light-collecting states when divergent light is incident, and FIG. 11C shows the respective light-collecting states when convergent light is incident. Note that FIG.
In FIG. 1, photodetectors are indicated by 4a and 4b for convenience.

[0006] Another conventional example is titled "Waveguide-type photodetector for optical integrated pickup". 3, 10p-ZN-8. This is also a detection principle similar to that of the conventional example described above, and the thickness of the buffer layer below the optical waveguide layer is tapered near the incident end face of the photodetector (the waveguide layer inclined portion 5 described above).
), And by reducing the thickness of the buffer layer on the photodetector surface, the absorption efficiency of the evanescent wave to the photodetector is improved.

[0007]

As shown in FIG. 10 described above, in the waveguide layer inclined portion 5 for guiding the guided light a in the optical waveguide layer 3 to the photodetector 4, the waveguide layer inclined portion 5 At the inclined start end 5a and the inclined end end 5b, part of the guided light a becomes radiation mode light M and is lost outside the optical waveguide layer 3. As described above, since the ratio of the radiation mode depends on the inclination angle of the waveguide layer inclined portion 5, the effective inclination angle with respect to the guided light a depends on the incident angle of the guided light a to the waveguide layer inclined portion 5. Fluctuates, and accordingly, the ratio of the radiation mode fluctuates, and the light utilization efficiency of the photodetector 4 becomes unstable due to the incident angle of the guided light. In addition, since the amount of waveguide light a absorbed by the substrate increases due to the attenuation of the thickness of the buffer layer 2, it is necessary to set the shape of the light receiving region of the photodetector 4 so that the light amount loss due to the attenuation is minimized. At this stage we have not seen any such considerations.

[0008]

According to the first aspect of the present invention, there is provided a waveguide having at least an optical waveguide layer and a photodetector formed on a substrate below the optical waveguide layer and detecting guided light. In the type photodetector, a waveguide layer inclined portion is formed on the guided light incident end side of the photodetector, and the shape of the inclined end of the waveguide layer inclined portion is the wavefront shape of the guided light on the inclined end. They were formed almost in agreement.

According to a second aspect of the present invention, in the first aspect of the invention, the waveguide light incident end of the photodetector is located forward of the inclined end of the waveguide layer inclined portion formed on the guided light incident end side. Placed.

According to the third aspect of the present invention, at least the optical coupler, the optical waveguide layer in which the guided light guided by the optical coupler travels, and the light provided in the optical path of the optical waveguide layer. In a waveguide type photodetector comprising a light collector and a light detector provided in the light guide layer for detecting the guided light collected by the light collector, the light detector A waveguide layer inclined portion was formed on the guided light incident end side, and the shape of the inclined end of the waveguide layer inclined portion was formed so as to substantially match the wavefront shape of the guided light on the inclined end.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the waveguide light incident end of the photodetector is positioned forward of the inclined end of the waveguide layer inclined portion formed on the guided light incident end side. Placed.

According to the fifth aspect of the present invention, the guided light propagating in the optical waveguide layer is guided to the inclined end of the inclined portion of the waveguide layer formed substantially in conformity with the wavefront shape of the guided light. The guided waveguide light is detected from the guided light incident end side of the photodetector located at the inclined end.

According to the sixth aspect of the present invention, the guided light propagating in the optical waveguide layer is guided to the inclined end of the inclined portion of the waveguide layer formed substantially in conformity with the wavefront shape of the guided light. The guided waveguide light is detected from the waveguide light incident end side of the photodetector disposed in front of the inclined end.

According to the seventh aspect of the present invention, the guided light guided and excited in the optical waveguide layer by the optical coupler is condensed by the light concentrator provided in the optical path of the optical waveguide layer. The illuminated guided light is guided to an inclined end of a waveguide layer inclined portion formed substantially in conformity with the wavefront shape of the guided light, and the guided light guided to the inclined end is detected by a light detector located at the inclined end. The light detection is performed from the waveguide light incident end side of the vessel.

According to the present invention, the guided light guided and excited in the optical waveguide layer by the optical coupler is condensed by the light concentrator provided in the optical path of the optical waveguide layer. The emitted guided light is guided to an inclined end of a waveguide layer inclined portion formed substantially in conformity with the wavefront shape of the guided light, and the guided light guided to the inclined end is disposed forward of the inclined end. The light detection is performed from the guided light incident end side of the photodetector.

[0016]

According to the first aspect of the present invention, the shape of the inclined end of the inclined waveguide light portion corresponding to the wavefront of the guided optical wave in the photodetector determines the position of the emissivity of the guided light emitted from the optical waveguide layer to the inclined end. It is possible to obtain a waveguide-type photodetector that suppresses fluctuations and has excellent stability of photodetection efficiency.

According to the second aspect of the present invention, since the light absorption by the substrate is prevented, the light detection efficiency and the stability can be further improved.

According to the third aspect of the present invention, the shape of the inclined end of the inclined waveguide light portion corresponding to the wavefront of the guided light in the photodetector determines the position of incidence of the emissivity of the guided light from the optical waveguide layer on the inclined end. This makes it possible to obtain a waveguide-type photodetector that suppresses fluctuations and has excellent stability of photodetection efficiency, and also facilitates optical coupling of external light to the optical waveguide layer and reflects and condenses guided light. Function can be enhanced.

According to the fourth aspect of the present invention, since the light absorption to the substrate is prevented, the light detection efficiency and the stability thereof can be further improved, and the external light can be transmitted to the optical waveguide layer. Optical coupling can be easily performed, and the function of reflecting and condensing guided light can be further enhanced.

According to the fifth aspect of the present invention, since the guided light is guided to the inclined end of the inclined waveguide light portion corresponding to the wavefront of the guided optical wave in the photodetector, the guided light is guided to the inclined end of the emissivity of the guided light from the optical waveguide layer. Can be suppressed due to the incident position, and the stability of light detection efficiency can be improved.

According to the sixth aspect of the present invention, by detecting the guided light with the structure in which the light absorption to the substrate is prevented, it is possible to further improve the light detection efficiency and the stability thereof.

According to the seventh aspect of the present invention, the inclination of the guided light inclined portion corresponding to the guided light wave front in the photodetector having the function of easily coupling the external light to the optical waveguide layer and having the function of reflecting and condensing the guided light. Since the guided light is guided to the end, the variation of the emissivity of the guided light from the optical waveguide layer due to the incident position on the inclined end can be suppressed, and the stability of the light detection efficiency can be improved.

According to the eighth aspect of the present invention, by detecting the guided light with the structure in which the light absorption to the substrate is prevented, the light detection efficiency and its stability can be further improved.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. The same parts as those in the conventional example (see FIGS. 10 and 11) are denoted by the same reference numerals.

In FIG. 1, a buffer layer 2 is provided on a substrate 1.
The optical waveguide layer 3 is laminated via the substrate. A waveguide layer inclined portion 5 is provided on the optical waveguide layer 3 located on the waveguide light incident end 4x side of the photodetector 4 formed on the surface of the substrate 1. The waveguide layer inclined portion 5 is formed with two inclined ends before and after an inclined start end 5a (between the ridge lines 1-1 ') and an inclined end end 5b (between the ridge lines 2-2'). These inclined start end 5a and inclined end 5b
Are formed in a state substantially coincident with the wavefront shape of the guided light a on the inclined end thereof.
In this case, the shape of the inclined end of the buffer layer 2 located below the inclined portion 5 of the optical waveguide layer 3 can be formed in the same manner as the inclined start end 5a and the inclined end 5b.

FIG. 2A shows a state in which the incident waveguide light a is convergent light. In this case, the shape of the inclined start end 5a and the inclined end 5b in the slab surface direction is convex on the incident side. It is shaped like a curve. FIG. 2 (b)
Shows a state in which the incident waveguide light a is divergent light. In this case, the inclined start end 5a and the inclined end 5b
The shape in the slab surface direction is a curved shape in which the incident side is concave. Thus, the shapes of the inclined start end 5a and the inclined end 5b are determined according to the wavefront shape of the guided light a.

In such a configuration, the guided light a propagating through the optical waveguide layer 3 is supplied to the inclined start end 5 a of the waveguide layer inclined portion 5.
The incident angle in the slab plane direction is equal to the incident angle at the inclined end 5b, and the incident light is perpendicular to the inclined end 5b. As a result, the guided light leak rates generated at the inclined start end 5a and the inclined end 5b are both constant. Thereafter, the guided light a is guided from the inclined end 5b through the optical waveguide layer 3 on the light receiving surface of the photodetector 4, and at this time, the evanescent component of the guided light a is transmitted to the light receiving surface via the thin film buffer layer 2. The light detection efficiency can be increased and the photodetector 4 can detect the light in a stable state.

As described above, the inclined end (inclined start end 5) of the guided light inclined portion 5 corresponding to the guided wave front in the photodetector 4.
a, the shape of the inclined terminal 5b) is made substantially coincident with the wavefront shape of the guided light a, whereby the variation of the emissivity of the guided light from the optical waveguide layer 3 due to the incident position on the inclined end is suppressed, and stable light detection is achieved. It can be carried out. In addition, a waveguide type photodetector having excellent stability of photodetection efficiency can be obtained.

Next, an embodiment of the present invention will be described with reference to FIGS. Note that the same reference numerals are used for the same portions as those in the embodiments of the first and fifth aspects of the present invention.

Here, in the waveguide type photodetector as shown in FIG. 3, the waveguide light incident end 4x of the photodetector 4 is connected to the inclined end of the waveguide layer inclined portion 5, that is, the inclined end 5b here.
It is arranged forward. FIG. 4A shows the respective shapes in the case of convergent light, and FIG. 4B shows the respective shapes in the case of divergent light.

If the shape of the waveguide light incident end 4x of the photodetector 4 deviates from the wavefront shape of the waveguide light a, the evanescent light is absorbed by the substrate 1 in the gap, causing a light quantity loss. As in the embodiment, by disposing the guided light incident end 4x in front of the inclined end 5b, there is no gap, so that the guided light a is not absorbed by the substrate 1 and the light receiving surface of the photodetector 4 The waveguide can be conducted with the detection efficiency further increased. Moreover, in this case, since the guided light a is perpendicularly incident on the inclined start end 5a and the inclined end 5b, the loss of light quantity generated at each inclined end is constant regardless of the incident position of the inclined end.

As described above, by arranging the guided light incident end 4x of the photodetector 4 ahead of the inclined end of the waveguide layer inclined portion 5, the light absorption to the substrate 1 is prevented. As a result, the light detection efficiency can be further increased, and the stability of the light detection efficiency can be further improved.

Next, an embodiment of the present invention will be described with reference to FIGS. Note that the same reference numerals are used for the same portions as those in the embodiments of the invention described in the first, second, fifth, and sixth aspects.

Here, as shown in FIG.
An optical waveguide layer 3 in which the guided light a guided by the optical coupler 7 travels; light collectors 8a and 8b provided in the optical path of the optical waveguide layer 3; The present invention relates to a waveguide type photodetector provided with photodetectors 4a and 4b provided in an optical waveguide layer 3 for detecting the guided light a collected by the detectors 8a and 8b. Also in this case, the above-described claim 1
Similarly to the invention described above, a waveguide layer inclined portion 5 is formed in the optical waveguide layer 3 located on the guided light incident end side 4x of the photodetectors 4a and 4b. The shapes of 5a and the inclined end 5b are formed in a state substantially matching the wavefront shape of the guided light a.

In such a configuration, first, FIG.
(A) to (c) will be described. FIG. 6A shows a state where the guided light a incident on the light collectors 8a and 8b is parallel, and the guided light a is located between the pair of photodetectors 4a and 4b.
Is collected. FIG. 6B shows a state where the guided light a incident on the light collectors 8a and 8b is diverging, and reaches the one photodetector 4b as convergent light. FIG. 6 (c)
Shows a state in which the guided light a incident on the light collectors 8a and 8b is converged. In this case, the divergent light is incident on the other photodetector 4a in the opposite direction to the divergent light. I do.

Now, the external light b incident through the optical coupler 7
Is guided to the optical waveguide layer 3, whereby the guided light a is collected by the light collectors 8 a and 8 b and guided to the photodetector 4 via the waveguide layer inclined portion 5. At this time, since the guided light a is vertically incident on the slab surface at the inclined start end 5a, the guided light leak rate generated at the inclined start end 5a is constant. Thereafter, the guided light a reaches the inclined end 5b and is vertically incident on the slab surface of this portion, and the guided light leak rate generated at this time becomes constant. Then, the guided light a that has traveled in this way is absorbed by the light receiving surface via the buffer layer 2 located above the photodetectors 4a and 4b, whereby light detection can be performed with high light detection efficiency. .

As described above, the inclined ends of the guided light inclined portions 5 corresponding to the guided light wavefronts of the photodetectors 4a and 4b have a shape substantially matching the wavefront shape of the guided light a.
Fluctuation of the emissivity of the guided light from the optical waveguide layer 3 due to the incident position on the inclined end can be suppressed, and a waveguide type photodetector excellent in the stability of the photodetection efficiency can be obtained. Moreover, in this case, the external light b can be easily optically coupled to the optical waveguide layer 3, and the guided light a
Can be configured to enhance the function of reflecting and condensing light.

Next, an embodiment of the present invention will be described. It should be noted that the above-mentioned claims 1, 2, 3, 3
The same reference numerals are used for the same portions as those of the embodiments of the invention described in 5, 6, and 7.

Here, in the waveguide type photodetector provided with the optical coupler 7 as shown in FIG.
Is arranged before the inclined end of the waveguide layer inclined portion 5, that is, in this case, ahead of the inclined end 5b.

Thus, in the process in which the guided light a reaches the inclined end 5b and guides the light through the optical waveguide layer 3 on the light receiving surfaces of the photodetectors 4a and 4b, the inclined end 5b and the guided light incident end 4x. Can be eliminated, so that the guided light a is not absorbed by the substrate 1 in such a gap, so that the photodetector 4a can be further enhanced in a state where the photodetection efficiency is further increased. , 4b.

As described above, by adopting a structure in which light absorption to the substrate 1 is blocked, the light detection efficiency and its stability can be further improved. Further, this makes it possible to easily couple the external light b to the optical waveguide layer 3 and further enhance the function of reflecting and condensing the guided light a.

Next, a first embodiment of the present invention will be described with reference to FIG. Note that the same reference numerals are used for the same portions as those of the above-described embodiments of the present invention.

FIG. 7 shows a state where the photodetectors 4a and 4b are located in front of the focal point of the guided light a propagating in the optical waveguide layer 3. At this time, since the wavefront shape of the converged guided light a has a concave wavefront shape with respect to the waveguide direction, the shape in the slab surface of the inclined start end 5a of the waveguide layer inclined portion 5 is made substantially coincident with this. The incident angle of the guided light a to the inclined start end 5a can be adjusted substantially perpendicularly. Moreover, the emissivity to the outside of the optical waveguide layer 3 at the inclined start end 5a in this case is constant regardless of the position of the inclined start end 5a.

Since the wavefront shape of the guided light a converging also at the inclined end 5b has a concave wavefront shape in the waveguide direction, the shape in the slab plane of the inclined end 5b is made substantially coincident with this. The angle of incidence of the guided light a on the inclined end 5b can be adjusted substantially vertically. At this time, the emissivity to the outside of the optical waveguide layer 3 at the inclined end 5b becomes constant regardless of the position of the inclined end 5b.

Further, by arranging the guided light incident ends 4x of the photodetectors 4a and 4b ahead of the inclined end 5b of the inclined portion 5 of the waveguide layer, the guided light from the inclined end 5b to the light receiving surface is formed. The loss of light quantity due to the absorption of the substrate 1 is eliminated, thereby improving the efficiency of detecting the guided light.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that the same reference numerals are used for the same portions as those of the above-described embodiments of the present invention.

FIG. 8 shows a state where the photodetectors 4a and 4b are located behind the focal point P of the guided light a propagating in the optical waveguide layer 3. At this time, since the wavefront shape of the diverging guided light a has a convex wavefront shape with respect to the guiding direction, the shape in the slab plane of the inclined start end 5a of the waveguide layer inclined portion 5 is made substantially coincident with this. The incident angle of the guided light a to the inclined start end 5a can be adjusted substantially perpendicularly. Moreover, the emissivity to the outside of the optical waveguide layer 3 at the inclined start end 5a in this case is constant regardless of the position of the inclined start end 5a.

Since the wavefront shape of the guided light a converging also at the inclined end 5b has a convex wavefront shape in the waveguide direction, the shape of the inclined end 5b in the slab plane is made to substantially match this. The incident angle of the guided light a to the inclined end 5b can be adjusted substantially vertically. At this time, the emissivity to the outside of the optical waveguide layer 3 at the inclined end 5b becomes constant regardless of the position of the inclined end 5b.

Furthermore, by arranging the guided light incident ends 4x of the photodetectors 4a and 4b ahead of the inclined end 5b of the inclined portion 5 of the waveguide layer, the guided light from the inclined end 5b to the light receiving surface is formed. The loss of light quantity due to the absorption of the substrate 1 is eliminated, thereby improving the efficiency of detecting the guided light.

Next, a third embodiment of the present invention will be described with reference to FIG. Here, as shown in FIG. 9A, a coupler prism is used as the optical coupler 7, and a slab waveguide including the buffer layer 2, the optical waveguide layer 3, and the cladding layer (electrode 6) is formed on the substrate 1. It was done. In this case, FIG.
As shown in (b), the shape of the inclined start end 5a and the inclined end 5b of the waveguide layer inclined portion 5 formed in front of the photodetectors 4a and 4b was made to substantially match the wavefront shape of the guided light a. Thereby, regardless of the parallelism of the light incident on the light collectors 8a and 8b,
Since the incident angle of the guided light to the inclined end of the waveguide layer inclined portion 5 is kept substantially vertical, and the emissivity of the guided light at the inclined end is constant regardless of the incident position of the guided light at the inclined end. It is possible to perform stable guided light detection with respect to the fluctuation of the degree.

Also in this case, the photodetectors 4a, 4b
Is arranged in front of the inclined end 5b of the waveguide layer inclined portion 5 in the waveguide process from the inclined end 5b to the optical waveguide layer 3 on the light receiving surfaces of the photodetectors 4a and 4b. In addition, the amount of light received on the light receiving surface can be improved without absorbing the guided light a into the substrate 1.

[0052]

According to the first aspect of the present invention, there is provided a waveguide type photodetector having at least an optical waveguide layer and a photodetector formed on a substrate below the optical waveguide layer and detecting guided light. In the above, a waveguide layer inclined portion is formed on the waveguide light incident end side of the photodetector, and the shape of the inclined end of the waveguide layer inclined portion is made substantially coincident with the wavefront shape of the guided light on the inclined end. Since it is formed, the variation of the emissivity of the guided light from the optical waveguide layer due to the incident position on the inclined end can be suppressed, and a waveguide type photodetector excellent in the stability of the photodetection efficiency can be obtained.

According to a second aspect of the present invention, in the first aspect, the waveguide light incident end of the photodetector is located forward of the inclined end of the waveguide layer inclined portion formed on the guided light incident end side. Because of the arrangement, the light detection efficiency and the stability can be further improved by adopting the structure in which the light absorption to the substrate is blocked.

According to a third aspect of the present invention, at least an optical coupler, an optical waveguide layer in which guided light guided and excited by the optical coupler travels, and light provided in an optical path of the optical waveguide layer. In a waveguide type photodetector comprising a light collector and a light detector provided in the light guide layer for detecting the guided light collected by the light collector, the light detector A waveguide layer inclined portion was formed on the waveguide light incident end side, and the shape of the inclined end of the waveguide layer inclined portion was formed so as to substantially match the wavefront shape of the guided light on the inclined end. The fluctuation of the emissivity of the guided light from the light source due to the incident position on the inclined end can be suppressed, and a waveguide-type photodetector with excellent stability of the photodetection efficiency can be obtained. Optical coupling can be easily performed, and the function of reflecting and condensing guided light can be enhanced.

According to a fourth aspect of the present invention, in the third aspect of the present invention, the waveguide light incident end of the photodetector is located forward of the inclined end of the waveguide layer inclined portion formed on the guided light incident end side. As a result, the light detection efficiency and stability can be further improved by adopting a structure in which light absorption to the substrate is blocked, and optical coupling of external light to the optical waveguide layer is facilitated. And the function of reflecting and condensing the guided light can be further enhanced.

According to the fifth aspect of the present invention, the guided light propagating in the optical waveguide layer is guided to the inclined end of the inclined portion of the waveguide layer which is formed substantially in conformity with the wavefront shape of the guided light. Since the guided waveguide light is detected from the guided light incident end side of the photodetector located at the inclined end, the variation in the emissivity of the guided light from the optical waveguide layer due to the incident position on the inclined end. And the stability of light detection efficiency can be improved.

According to a sixth aspect of the present invention, the guided light propagating in the optical waveguide layer is guided to the inclined end of the inclined portion of the waveguide layer formed substantially in conformity with the wavefront shape of the guided light. Since the guided waveguide light is detected from the guided light incident end side of the photodetector arranged before the inclined end, the guided light is guided by the structure in which light absorption to the substrate is blocked. By detecting the wave light, the light detection efficiency and its stability can be further improved.

According to a seventh aspect of the present invention, the guided light guided and excited in the optical waveguide layer by the optical coupler is condensed by a light concentrator provided in the optical path of the optical waveguide layer. The illuminated guided light is guided to an inclined end of a waveguide layer inclined portion formed substantially in conformity with the wavefront shape of the guided light, and the guided light guided to the inclined end is detected by a light detector located at the inclined end. The light detection is performed from the waveguide light incident end side of the detector, so that the optical coupling of the external light to the optical waveguide layer is easy and the guided light wavefront in the photodetector having the function of reflecting and condensing the guided light. By guiding the guided light to the inclined end of the guided light inclined part corresponding to the above, the fluctuation of the emissivity of the guided light from the optical waveguide layer due to the incident position on the inclined end is suppressed, and the stability of the light detection efficiency is improved. Is what you can do.

According to an eighth aspect of the present invention, the guided light guided and excited in the optical waveguide layer by the optical coupler is condensed by a light concentrator provided in the optical path of the optical waveguide layer. The emitted guided light is guided to an inclined end of a waveguide layer inclined portion formed substantially in conformity with the wavefront shape of the guided light, and the guided light guided to the inclined end is disposed forward of the inclined end. Since the light detection is performed from the guided light incident end side of the photodetector, the light detection efficiency and stability can be improved by detecting the guided light with such a structure that the light absorption to the substrate is blocked. It can be further improved.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a configuration of a waveguide type photodetector according to an embodiment of the present invention.

FIG. 2A is a plan view showing an inclined end shape of a guided light inclined portion when the guided light is a convergent wavefront, and FIG. 2B is an inclined end of the guided light inclined portion when the guided light is a divergent wavefront. It is a top view which shows a shape.

FIG. 3 is a sectional view showing a configuration of a waveguide type photodetector according to an embodiment of the present invention.

FIG. 4A is a plan view showing an inclined end shape of a guided light inclined portion when the guided light is a convergent wavefront, and FIG. 4B is an inclined end of the guided light inclined portion when the guided light is a divergent wavefront. It is a top view which shows a shape.

FIG. 5 is a sectional view showing a configuration of a waveguide type photodetector according to an embodiment of the present invention.

6A is a plan view showing the shape of a waveguide type photodetector when the guided light is parallel light, and FIG. 6B is a plan view showing the shape of the waveguide type photodetector when the guided light is divergent light. FIG. 3C is a plan view showing the shape of the waveguide type photodetector when the guided light is convergent light.

FIG. 7 is a plan view showing a first specific example.

FIG. 8 is a plan view showing a second specific example.

FIG. 9 is a plan view showing a third specific example.

FIG. 10A is a cross-sectional view showing a conventional example, and FIG. 10B is a plan view of the photodetector.

11A is a plan view showing the shape of a waveguide-type photodetector when the guided light is parallel light, and FIG. 11B is a plan view showing the shape of the waveguide-type photodetector when the guided light is divergent light. FIG. 3C is a plan view showing the shape of the waveguide type photodetector when the guided light is convergent light.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 3 Optical waveguide layer 4, 4a, 4b Photodetector 4x Guided light incidence end 5 Waveguide layer inclined part 5a, 5b Inclined end 7 Optical coupler 8a, 8b Optical concentrator

Claims (8)

(57) [Claims] 1. A waveguide-type photodetector having at least an optical waveguide layer and a photodetector formed on a substrate below the optical waveguide layer and detecting guided light, wherein a light guide for the photodetector is provided. A waveguide layer inclined portion is formed on the wave light incident end side, and the shape of the inclined end of the waveguide layer inclined portion is formed so as to substantially match the wavefront shape of the guided light on the inclined end. Wave path type photodetector. 2. The waveguide according to claim 1, wherein the waveguide light incident end of the photodetector is disposed forward of the inclined end of the waveguide layer inclined portion formed on the guided light incident end side. Type photodetector. 3. An optical coupler, an optical waveguide layer in which guided light guided and excited by the optical coupler travels, an optical concentrator provided in an optical path of the optical waveguide layer, and And a photodetector provided in the optical waveguide layer for detecting the guided light collected by the light concentrator. A waveguide type photodetector, wherein a waveguide layer inclined portion is formed, and the shape of the inclined end of the waveguide layer inclined portion is formed so as to substantially match the wavefront shape of the guided light on the inclined end. . 4. The waveguide according to claim 3, wherein the guided light incident end of the photodetector is disposed forward of the inclined end of the waveguide layer inclined portion formed on the guided light incident end side. Type photodetector. 5. The guided light propagating in the optical waveguide layer is guided to an inclined end of a waveguide layer inclined portion formed substantially in conformity with the wavefront shape of the guided light, and the guided light guided to the inclined end. Wherein the light detection is performed from the guided light incident end side of the photodetector located at the inclined end thereof. 6. The guided light propagating in the optical waveguide layer is guided to an inclined end of a waveguide layer inclined portion formed substantially in accordance with the wavefront shape of the guided light, and the guided light guided to the inclined end. Wherein the light is detected from the guided light incident end side of the photodetector disposed in front of the inclined end. 7. A waveguide light guided and excited in an optical waveguide layer by an optical coupler is condensed by an optical concentrator provided in an optical path of the optical waveguide layer, and the condensed waveguide light is collected. The guided light is guided to an inclined end of a waveguide layer inclined portion formed substantially in conformity with the wavefront shape of the guided light, and the guided light guided to the inclined end is a guided light incident end of a photodetector located at the inclined end. A waveguide light detection method, wherein light detection is performed from the side. 8. A waveguide light guided and excited in an optical waveguide layer by an optical coupler is condensed by a light concentrator provided in an optical path of the optical waveguide layer, and the condensed waveguide light is collected. The waveguide is guided to the inclined end of the inclined portion of the waveguide layer formed substantially in conformity with the wavefront shape of the guided light, and the guided light guided to the inclined end of the photodetector disposed in front of the inclined end. A guided light detection method, wherein light detection is performed from the guided light incident end side.