JP2010287623A - Semiconductor light-receiving element and method of manufacturing semiconductor light-receiving element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor light-receiving element which is high in durability and has high-speed response performance, and to provide a method of manufacturing the same. <P>SOLUTION: The semiconductor light-receiving element includes: an optical branching filter 12 which includes an input part 121, a first output part 122 and a second output part 123, and branches a light beam inputted from the input part 121 into light beams having lower intensity than the incident light beam without polarizing or demultiplying it and outputs the beams from the first output part 122 and second output part 123; a first optical waveguide 13A which propagates the light beam from the first output part 122; a second optical waveguide 13B which propagates the light beam from the second output part 123; and a semiconductor light absorption layer 142 connected to a light projection-side end face of the first optical waveguide 13A and a light projection-side end face of the second optical waveguide 13B. The light beam from the first optical waveguide 13A is incident on the semiconductor light absorption layer 142 from a direction different from that of the light beam from the second optical waveguide 13B. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a semiconductor light receiving element and a method for manufacturing the semiconductor light receiving element.

With the explosive spread of the Internet, the amount of communication is increasing rapidly. This is supported by optical communication technology. In such optical communication technology, optical communication is performed by cooperation of a semiconductor laser, an optical fiber, and a semiconductor light receiving element. In a semiconductor laser, an electrical signal is converted into an optical signal. The optical fiber transmits the converted optical signal. The semiconductor light receiving element receives a signal output from the optical fiber and converts it into an electric signal.
Compared with the case where an electrical signal is sent, the optical fiber has a lower attenuation rate due to transmission and can be sent farther with a small power.
However, the attenuation of optical power accompanying transmission is not zero. The attenuation associated with transmission in the communication wavelength band is about 0.2 to 0.4 dB / km. For this reason, in order to transmit farther, it is necessary to increase the efficiency of the light receiving element.
Here, a light receiving element as shown in FIG. 15 has been proposed as the light receiving element (see Non-Patent Document 1). This light receiving element is formed by laminating an n-type InP layer 902, a light absorption layer 903, and a p-type InP layer 904. Since light enters from the edge face and is absorbed while being guided in parallel with the light absorption layer 903, it is said that even a thin light absorption layer 903 can realize high light receiving efficiency.

JP-A-5-37006

J.E.Bowers, et al. Lightwave Technol., Vol. Lt-5, No. 10, 1339 (1987) T. Takeuchi, et. Al., Electron. Lett., 36, 972 (2000)

However, the light receiving element disclosed in Non-Patent Document 1 has a problem that it is inferior in durability.
This will be described with reference to FIGS. 16 and 17.
FIG. 16 is a diagram showing the dependence of quantum efficiency on the waveguide length. FIG. 17 shows the relative intensity of the photocurrent density at each position in the waveguide direction. Here, the waveguide length is the length of the absorption layer region shown in FIG. 15 in the waveguide direction.
It can be seen that the longer the waveguide length is, the higher the quantum efficiency is, and the rate of increase of the efficiency increases rapidly when the waveguide length is 10 μm or less. This indicates that most of the incident light is absorbed by the end face. Therefore, the photocurrent is concentrated on the waveguide end face of 10 μm or less as can be seen from FIG. Since the photocurrent density is concentrated in the light input end face region in this way, the device may be destroyed when high intensity light is input. In particular, when an EDFA (Erbium Doped Fiber Amplifier) that amplifies optical power attenuated during transmission is introduced in the transmission line, high intensity light is input to the light receiving element, so that the light receiving element is not destroyed. High durability is required.

In order to solve such a problem, it is conceivable to use a light receiving element that receives an evanescent wave (see, for example, Non-Patent Document 2). FIG. 18 is a cross-sectional structure diagram of a light receiving element that receives an evanescent wave. This light receiving element has a structure in which a guide layer 803 is formed on an InP substrate 802, and a light absorption layer 804 and a semiconductor layer 805 are integrated on the guide layer 803, and incident light is spotted while being guided through the guide layer 803. It is absorbed by the absorption layer 804 so as to be emitted.
FIG. 19 shows the calculation result of the relationship between the absorption layer length and the efficiency of the evanescent light receiving element. The absorption layer length L is defined by the length of the absorption layer 804 laminated on the guide layer 803, as shown in FIG.
FIG. 16 showing the calculation result of the dependence of the efficiency of the waveguide type light receiving element on the waveguide length and FIG. 19 showing the calculation result of the evanescent type light receiving element are compared, and in order to obtain 80% efficiency, the evanescent type light receiving element is obtained. In the element, an absorption layer of 30 μm, which is twice as long as the waveguide type light receiving element, is required.
That is, in order to obtain the same light receiving efficiency, the length of the absorption layer is increased in the evanescent structure. This causes a decrease in high-speed response performance, which is the basic performance of the light receiving element.
Patent Document 1 discloses a method for photoelectric conversion by separating incident light into TE waves or TM waves. Also in this case, when the incident light is only the TE wave, and when only the TM wave is used, the incident light is collected on one end face of the photoelectric conversion portion, so that the photoelectric conversion portion is easily deteriorated and durability is deteriorated. .

  The present invention provides a semiconductor light-receiving element having high durability and high-speed response performance, and a method for manufacturing the same.

  According to the present invention, an input unit, a first output unit, and a second output unit, the input light from the input unit is branched into light having a lower intensity than the input light, and the first An output unit, an optical demultiplexer that outputs from the second output unit, a first optical waveguide that propagates light from the first output unit, and a second optical waveguide that propagates light from the second output unit And a semiconductor light absorption layer connected to the light emission side end face of the first optical waveguide and the light emission side end face of the second optical waveguide, and light from the first optical waveguide is transmitted from the second optical waveguide. There is provided a semiconductor light receiving element that is incident on the semiconductor light absorption layer from a direction different from that of the light.

  Further, according to the present invention, the light including the input unit, the first output unit, and the second output unit, and having a lower intensity than the input light without polarization separation of the input light input from the input unit Branching into the first output unit, the optical demultiplexer that outputs from the second output unit, the first optical waveguide that propagates the light from the first output unit, and the light from the second output unit And a semiconductor light absorption layer connected to the light emitting side end surface of the first optical waveguide and the light emitting side end surface of the second optical waveguide, and from the first optical waveguide A method of manufacturing a semiconductor light receiving element that forms the first optical waveguide and the second optical waveguide so that light is incident on the semiconductor light absorption layer from a direction different from the light from the second optical waveguide can be provided. .

  ADVANTAGE OF THE INVENTION According to this invention, durability and the semiconductor light receiving element which has a high-speed response performance, and its manufacturing method are provided.

It is a top view which shows the semiconductor light receiving element concerning 1st embodiment of this invention. It is AA 'sectional drawing of FIG. It is BB 'sectional drawing of FIG. It is CC 'sectional drawing of FIG. 1, and DD' sectional drawing. It is EE 'sectional drawing of FIG. It is FF 'sectional drawing of FIG. It is a top view which shows the semiconductor light receiving element concerning 2nd embodiment of this invention. FIG. 8 is a cross-sectional view taken along a line AA ′, a cross-sectional view taken along a line CC ′, and a cross-sectional view taken along a line DD ′ in FIG. 7. It is BB 'sectional drawing of FIG. It is EE 'sectional drawing of FIG. It is sectional drawing which shows a manufacturing process. It is sectional drawing which shows a manufacturing process. It is a top view which shows the semiconductor light receiving element concerning 3rd embodiment of this invention. It is sectional drawing which shows the principal part of the semiconductor light receiving element concerning 4th embodiment of this invention. It is sectional drawing which shows the semiconductor light receiving element concerning background art. It is a figure which shows waveguide length and quantum efficiency. It is a figure which shows waveguide length and a photocurrent density. It is sectional drawing which shows the semiconductor light receiving element concerning background art. It is a figure which shows absorption layer length and a photocurrent density.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, the same components are denoted by the same reference numerals, and detailed description thereof is appropriately omitted so as not to overlap.
(First embodiment)
A first embodiment of the present invention will be described with reference to FIGS.
First, an outline of the semiconductor light receiving element of this embodiment will be described.
The semiconductor light receiving element 1 according to the present embodiment includes an input unit 121, a first output unit 122, and a second output unit 123. The input light input from the input unit 121 is separated from the input light without polarization separation. An optical demultiplexer 12 that is branched into low-intensity light and output from the first output unit 122 and the second output unit 123, the first optical waveguide 13A that propagates the light from the first output unit 122, and the second A second optical waveguide 13B for propagating light from the output unit 123, and a semiconductor light absorption layer 142 connected to the light emission side end face of the first optical waveguide 13A and the light emission side end face of the second optical waveguide 13B are provided.
The light from the first optical waveguide 13A enters the semiconductor light absorption layer 142 from a direction different from the light from the second optical waveguide 13B.

Next, the semiconductor light receiving element 1 of the present embodiment will be described in detail.
The semiconductor light receiving element 1 is formed by laminating an optical demultiplexer 12, optical waveguides 13A and 13B, and a light receiving element portion 14 serving as a light receiving region on a semiconductor substrate 11.

The optical demultiplexer 12 is composed of a multimode interference optical waveguide (MMI).
In this embodiment, one input part 121 and two output parts 122 and 123 are formed in the multimode interference optical waveguide.
The input optical waveguide 15 is connected to the input unit 121. The optical waveguide 15 is for making light incident on the input unit 121. FIG. 2 shows a cross-sectional view in the AA ′ direction of FIG. A 1 μm thick InP layer 151A laminated on the semiconductor substrate 11, a 0.2 μm thick InGaAsP layer 151B laminated on the InP layer 151A, and a 1 μm thick InP layer laminated on the InGaAsP layer 151B. 151C is provided. The optical waveguide 15 has a mesa type waveguide structure, and has a mesa width W of 2 μm and a mesa height h of 3 μm.
Note that the composition, thickness, mesa width, height, and the like of each semiconductor layer are merely examples, and the present invention is not limited thereto. Light from a signal source such as a semiconductor laser is input to the optical waveguide 15 having the InGaAsP layer 151B as a core.

The multimode interference optical waveguide (optical demultiplexer 12) has a rectangular interference region. The input unit 121 is formed on one side of the rectangle, and the output units 122 and 123 are formed on the other side facing each other.
FIG. 3 is a cross-sectional view of the multimode interference optical waveguide, and is a cross-sectional view in the BB ′ direction of FIG. 1. As shown in FIG. 3, the multimode interference optical waveguide has a mesa structure in which an InP layer 124A, an InGaAsP layer 124B having a composition wavelength of 1.2 μm, and an InP layer 124C are stacked on a semiconductor substrate 11. The mesa width W is, for example, 10 μm, and the mesa height h is, for example, 3 μm. At this time, the length L (MMI length) of the multimode interference optical waveguide in FIG. 1 is, for example, 100 μm.
Light from the input unit 121 propagates through a multimode interference waveguide having the InGaAsP layer 124B as a core.

  The first optical waveguide 13A is connected to the output part 122 of the multimode interference optical waveguide. The second optical waveguide 13B is connected to the output portion 123 of the multimode interference optical waveguide. The first optical waveguide 13A and the second optical waveguide 13B have the same layer structure, and a CC ′ sectional view and a DD ′ sectional view of FIG. 1 are shown in FIG. Each of the first optical waveguide 13A and the second optical waveguide 13B has a laminated structure in which an InP layer 131, an InGaAsP layer 132 having a composition wavelength of 1.2 μm, and an InP layer 133 are laminated on the semiconductor substrate 11 in this order, and has a mesa structure. It is. Light from the output units 122 and 123 propagates in the InGaAsP layer 132, respectively. The light receiving element portion 14 is connected to the light emission side end face of the first optical waveguide 13A and the light emission side end face of the second optical waveguide 13B.

As shown in FIG. 5, the light receiving element portion 14 is formed by laminating an n-type InP layer 141, an i-InGaAs layer 142 that is a light absorption layer, and a p-type InP layer 143 in this order on the semiconductor substrate 11. The mesa structure. The mesa width W is, for example, 3.0 μm, and the mesa height h is, for example, 3 μm. The p-type InP layer 143 has a thickness of 1 μm, for example, and the i-InGaAs layer 142 which is a light absorption layer has a thickness of 0.6 μm, for example. A p-type electrode 144 is formed immediately above the p-type InP layer 143, and an n-type electrode 145 is formed on the n-type InP layer 141. 5 is a cross-sectional view taken along the line EE ′ of FIG.
As shown in FIG. 6, the light absorption layer 142 is connected to the light emitting side end face of the InGaAsP layer 132 of the first optical waveguide 13A and the second optical waveguide 13B, and the InGaAsP of the first optical waveguide 13A and the second optical waveguide 13B. Absorbs light from layer 132. For this reason, the InGaAsP layer 132 and the light absorption layer 142 are stacked at substantially the same height in the stacking direction. Light from the first optical waveguide 13A and the second optical waveguide 13B is incident on different end faces of the light absorption layer 142, respectively. In the present embodiment, light enters from the opposite end surfaces of the light absorption layer 142. FIG. 6 is a cross-sectional view taken along the line FF ′ of FIG.

  The semiconductor light receiving element 1 as described above can be manufactured, for example, as follows. When forming the optical waveguide 15, the first optical waveguide 13A, the second optical waveguide 13B, and the multimode interference waveguide 12, the optical waveguide 15, the first optical waveguide 13A, the second optical waveguide 13B, The semiconductor layers constituting the multimode interference waveguide 12 are stacked. Thereafter, the region other than the region where the light receiving element portion 14 is formed is covered with a mask, and the semiconductor layer grown as described above is removed. Next, a semiconductor layer is selectively formed (selectively grown) on a portion that becomes the light receiving element portion 14 to form the light receiving element portion 14. Next, the grown semiconductor layers are selectively etched or the like so as to form the optical waveguide 15, the first optical waveguide 13A, the second optical waveguide 13B, the multimode interference waveguide 12, and the light receiving element portion 14. Remove. Thereby, the above-described semiconductor light receiving element 1 in which the light from the first optical waveguide 13A enters the semiconductor light absorbing layer 142 from a direction different from the light from the second optical waveguide 13B can be obtained.

Next, the operation of the light receiving element of this embodiment will be described.
Input light enters the multimode interference optical waveguide 12 via the optical waveguide 15. Then, the light is emitted from the multimode interference optical waveguide 12 to the first optical waveguide 13A and the second optical waveguide 13B.
At this time, when the incident light power incident on the multimode interference optical waveguide 12 is 1 mW, 0.5 mW of power is coupled to each of the output units 122 and 123. That is, light having half the power of the light input to the input unit 121 is incident on the output units 122 and 123, and light having substantially the same intensity is emitted from the output units 122 and 123. . The signal light emitted from the output unit 122 propagates through the first optical waveguide 13A and enters the light receiving element unit 14 from the emission side end face of the first optical waveguide 13A. On the other hand, the signal light emitted from the output part 123 is incident on the light receiving element part 14 via the emission side end face of the second optical waveguide 13B. As shown in FIG. 6, since signal light enters the light absorption layer 142 of the light receiving element portion 14 from different directions (in the opposite direction in this embodiment), the photocurrent density at the end surface of the light absorption layer 142 is reduced. It becomes possible to halve. As a result, it is possible to realize excellent high light input characteristics.

  In addition, light having a power half that of the light input to the input unit 121 is incident on the output units 122 and 123, so that the light is connected to the second optical waveguide 13 </ b> B of the light absorption layer 142 of the light receiving element unit 14. Thus, light having the same power is incident on both the end face connected to the first optical waveguide 13A of the light absorption layer 142 and the end face connected to the first optical waveguide 13A. Thereby, it can suppress that one light incident end surface of the light absorption layer 142 deteriorates too much compared with the other light incident end surface.

In the present embodiment, light emitted from the emission-side end faces of the optical waveguides 13A and 13B (end faces orthogonal to the light propagation direction of the optical waveguides 13A and 13B) is applied to the end face of the light absorption layer 142 of the light-receiving element portion 14. Since the semiconductor light receiving element 1 is introduced, the semiconductor light receiving element 1 has high-speed response performance.
That is, since the light receiving element portion 14 does not absorb the evanescent wave while propagating light, it is possible to prevent the high-speed response performance from being deteriorated.

Here, Patent Document 1 discloses a method of photoelectrically converting incident light by polarization separation into TE wave or TM wave. In this case, when the incident light is only the TE wave, and when only the TM wave is used, the incident light is collected on one end face of the photoelectric conversion portion, so that the photoelectric conversion portion is easily deteriorated and the durability is deteriorated.
On the other hand, in this embodiment, the optical demultiplexer 12 branches the incident light into light having a lower intensity than the incident light without polarization separation. Thereby, even if the incident light is only a TE wave and a TM wave, it is branched by the optical demultiplexer 12, so that it is possible to reliably realize excellent high light resistance.

(Second embodiment)
In the first embodiment described above, the case where the optical waveguides 15, 13A, 13B and the multimode interference waveguide and the light receiving element portion 14 have a mesa structure has been described, but the present invention is not limited to this.
In this embodiment, the optical waveguide, the multimode interference waveguide, and the light receiving element portion are embedded.
The semiconductor light receiving element is the same as that of the above embodiment except that it is a buried type.
FIG. 7 shows a plan view of the semiconductor light receiving element 2. Similarly to the first embodiment, the semiconductor light receiving element 2 is also formed by laminating optical waveguides 25, 23A, 23B, a multimode interference waveguide 22, and a light receiving element portion 24 on the semiconductor substrate 11.
FIG. 8 corresponds to a cross-sectional view taken along the lines AA ′, DD ′, and CC ′ of FIG. The optical waveguide 25 has a structure in which an InGaAsP layer 151 having a wavelength composition of 1.2 μm serving as a waveguide core is embedded with an InP layer 200. Similarly, the optical waveguides 23A and 23B also have a structure in which an InGaAsP layer 132 having a wavelength composition of 1.2 μm to be a waveguide core is embedded with an InP layer 200. The waveguide core has a width W of 3 μm and a layer thickness h of 2 μm. FIG. 9 is a diagram corresponding to the BB ′ sectional view of FIG. 7. The multimode interference waveguide 22 also has a structure in which an InGaAsP layer 124B having a wavelength composition of 1.2 μm serving as a waveguide core is embedded with an InP layer 221.
FIG. 10 is a cross-sectional view corresponding to the cross section EE ′ of FIG. The light receiving element portion 24 is formed with a stacked structure of an n-type InP layer 141, an i-InGaAs layer 142 that is a light absorption layer, and a p-type InP layer 143 as in the above-described embodiment, and this stacked structure is formed of Fe or Ru as an impurity. And embedded in a semi-insulating InP layer 247.

Such a semiconductor light receiving element 2 can be manufactured as follows, for example.
As shown in FIG. 11A, an InP layer 291, an InGaAsP layer 290, and an InP layer 292 are stacked on the semiconductor substrate 11. The InP layer 291 and the InP layer 292 become part of the InP layer 200 in FIG. 8 and the InP layer 221 in FIG. The InGaAsP layer 290 becomes the InGaAsP layers 132 and 151 in FIG. 8 and the InGaAsP layer 124B in FIG. Next, a region other than the region where the light receiving element portion 24 is formed is covered with a mask, and the semiconductor layer stacked above is removed. Next, as shown in FIG. 11B, an n-type InP layer 294, an i-type InGaAs layer 293, and a p-type InP layer 295 having a PIN structure are selectively grown in a region to be the light-receiving element portion 24. The n-type InP layer 294 becomes the n-type InP layer 141 in FIG. 10, the i-type InGaAs layer 293 becomes the i-type InGaAs layer 142 in FIG. 10, and the p-type InP layer 295 becomes the p-type InP layer 143 in FIG.
Next, the grown semiconductor layers are selectively etched by etching or the like so as to form the optical waveguide 25, the first optical waveguide 23A, the second optical waveguide 23B, the multimode interference waveguide 22, and the light receiving element portion 24. Remove. FIGS. 12A and 12B are views for explaining the structure after removal by etching or the like. FIG. 12 (A) is a cross-sectional view in the middle of production (after etching) at positions AA ′, CC ′, and DD ′ in FIG. The cross section BB ′ in FIG. 7 is the same except that the mesa width W is widened. FIG. 12B is a cross-sectional view in the middle of production (after etching) of the position of E-E ′ serving as the light receiving region in FIG.
Thereafter, the region removed by the above etching is filled with In (P) that contains Ru (ruthenium) or Fe as an impurity. FIGS. 12C and 12D show shapes after FIGS. 12A and 12B are embedded with the Fe—InP layer 296, respectively. This Fe—InP layer is a part of the InP layer 200 in FIG. 8, the InP layer 221 in FIG. 9, and the InP layer 247 in FIG. Further, the InP layer is embedded to complete the InP layer 200 in FIG. 8, the InP layer 221 in FIG. 9, and the InP layer 247 in FIG.

In such a buried structure light receiving element, the same effect as that of the first embodiment can be obtained, and an excellent high light input resistance can be realized.

(Third embodiment)
A third embodiment of the present invention will be described with reference to FIG.
In the present embodiment, two input portions 321 and 322 are formed in the multimode interference optical waveguide which is the optical demultiplexer 32. That is, the multimode interference optical waveguide is a 2 × 2 multimode interference waveguide having two input portions and two output portions. Input optical waveguides 15 are connected to the input portions 321 and 322 of the optical demultiplexer 32, respectively. Other points are the same as in the first embodiment.
Here, the signal light incident on the multimode interference optical waveguide from one input unit 321 is divided in power and output from the output units 122 and 123, respectively. When the incident light power is 1 mW, half power light, that is, 0.5 mW power is coupled to each of the output units 122 and 123. Thereafter, the light is incident on the light absorption layer 142 of the light receiving element portion 14 from a different direction (here, the opposite direction) and is absorbed. As a result, it is possible to realize excellent high light input characteristics.
A light source (optical signal source) is connected to one input unit 321, but no light source is connected to the other input unit 322 and no light is input thereto. That is, the input unit 322 is not connected.

  Furthermore, in the present embodiment, reflected return light to the light source (optical signal source) can be suppressed. Since the refractive index differs at the connection interface between the optical waveguides 13A and 13B and the light absorption layer 142, reflection occurs. For example, in FIG. 13, part of the signal light from the output units 122 and 123 is reflected at the connection interface between the optical waveguide 13 </ b> A and the light receiving element unit 14 and at the connection interface between the optical waveguide 13 </ b> B and the light receiving element unit 14. The reflected light returns through the propagated optical waveguides 13A and 13B, enters the multimode interference waveguide 32 from the output sections 122 and 123, and is coupled to the unconnected input section 322. That is, it is possible to suppress the reflected return light from returning to the light source (optical signal source) side.

(Fourth embodiment)
A fourth embodiment of the present invention will be described with reference to FIG.
The present embodiment is characterized in that the light receiving element portion is an avalanche photodiode having a multiplication layer. Other points are the same as in the first embodiment.
FIG. 14 is a cross-sectional view of the light receiving element portion. The light receiving element portion includes an n-type InP layer 41, an InAlAs multiplication layer 42, an InAlAs electric field relaxation layer 43, an InGaAs absorption layer 44, and a p-type InP layer 45. Other points are the same as in the first embodiment.
In the fourth embodiment, the same effect as that of the first embodiment can be obtained, and the internal gain for multiplying the carriers in the multiplication layer of the light receiving region can be obtained, so that the light receiving sensitivity can be improved.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
For example, in each of the above embodiments, two output units are formed in the multimode interference waveguide, but the present invention is not limited to this, and the number of output units may be three or more. A waveguide may be connected to each output portion and guided to the light absorption region. However, it is preferable that light from each waveguide is input to the light absorption region from different directions.
Furthermore, in the above-described embodiment, the optical demultiplexer has two input units. However, the present invention is not limited to this, and there may be three or more.
Further, the composition, thickness, mesa width, height, and the like of each semiconductor layer described in the above embodiments are merely examples, and the present invention is not limited thereto.

DESCRIPTION OF SYMBOLS 1 Semiconductor light receiving element 2 Semiconductor light receiving element 11 Semiconductor substrate 12 Optical demultiplexer (multimode interference waveguide)
13A First optical waveguide 13B Second optical waveguide 14 Light-receiving element portion 15 Optical waveguide 22 Optical demultiplexer (multimode interference waveguide)
23A First optical waveguide 23B Second optical waveguide 24 Light receiving element portion 25 Optical waveguide 32 Optical demultiplexer (multimode interference waveguide)
41 InP layer 42 Multiplication layer 43 Electric field relaxation layer 44 Absorption layer 45 InP layer 121 Input part 121D InP layer 122 First output part 123 Second output part 124A InP layer 124B InGaAsP layer 124C InP layer 131 InP layer 132 InGaAsP layer 133 InP Layer 141 InP layer 142 semiconductor light absorption layer 142 absorption layer 143 InP layer 144 electrode 145 electrode 151A InP layer 151B InGaAsP layer 151C InP layer 200 InP layer 221 InP layer 247 InP layer 290 InGaAsP layer 291 InP layer 292 InP layer 293 i-InGaAs Layer 294 n-InP layer 295 p-InP layer 296 Fe-InP layer 321 input unit 322 input unit 802 substrate 803 guide layer 804 light absorption layer 804 absorption layer 805 semiconductor layer 902 InP layer 903 light absorption layer

Claims (6)

The first output unit includes an input unit, a first output unit, and a second output unit, and splits the input light from the input unit into light having a lower intensity than the input light without polarization separation. An optical demultiplexer that outputs from the second output unit;
A first optical waveguide for propagating light from the first output portion; a second optical waveguide for propagating light from the second output portion;
A semiconductor light absorption layer connected to the light emission side end face of the first optical waveguide and the light emission side end face of the second optical waveguide;
A semiconductor light receiving element in which light from the first optical waveguide enters the semiconductor light absorption layer from a direction different from that of light from the second optical waveguide. The semiconductor light receiving element according to claim 1,
A semiconductor light receiving element in which the intensity of light emitted from the first output unit and the second output unit of the optical demultiplexer is substantially the same. The semiconductor light-receiving element according to claim 1 or 2,
A semiconductor light receiving element in which the optical demultiplexer has a multimode interference (MMI) structure. In the semiconductor light receiving element according to any one of claims 1 to 3,
The optical demultiplexer includes two or more input units,
A semiconductor light receiving element in which a light source is connected to one input unit and no light source is connected to the other input unit. In the semiconductor light receiving element according to any one of claims 1 to 4,
A semiconductor light receiving element in which an avalanche photodiode including the semiconductor light absorption layer is formed. The first output unit includes an input unit, a first output unit, and a second output unit, and splits the input light from the input unit into light having a lower intensity than the input light without polarization separation. An optical demultiplexer that outputs from the second output unit;
A first optical waveguide for propagating light from the first output portion; a second optical waveguide for propagating light from the second output portion;
Forming a light emitting side end face of the first optical waveguide and a semiconductor light absorbing layer connected to the light emitting side end face of the second optical waveguide;
Semiconductor light receiving that forms the first optical waveguide and the second optical waveguide so that the light from the first optical waveguide enters the semiconductor light absorption layer from a direction different from the light from the second optical waveguide. Device manufacturing method.

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