JP7412834B1 - optical power converter - Google Patents

Abstract

An object of the present invention is to provide an optical power supply converter that improves the output by improving the utilization efficiency of light from an optical fiber cable in a divided circular light receiving section to increase the output voltage. [Solution] In an optical power supply converter that converts light from an optical fiber cable into a photocurrent using a semiconductor light receiving element (10) and outputs the photocurrent, a circular light receiving part (12) of the semiconductor light receiving element (10) is connected to the circular light receiving part. A circular photodiode (14a) and one or more circular photodiodes (14b) divided by a plurality of circular isolation grooves concentric with (12), and a plurality of radial grooves on the outside of the circular photodiode (14b). It has a plurality of radial photodiodes (16) divided by isolation grooves, and a circular photodiode (14a), an annular photodiode (14b), and a plurality of radial photodiodes (16) are arranged according to the light intensity distribution of the light. Based on this, the light-receiving areas were set so that the amount of light received was equal to each other, and the light-receiving areas were connected in series by a plurality of conductive members (25).

Description

The present invention relates to an optical power supply converter that converts light input via an optical fiber cable into power and supplies the power.

In special environments, such as remote locations without power supply equipment, environments where weak electromagnetic fields from power supply cause noise, environments that require explosion protection, and inside ultra-high voltage equipment where electrical interactions occur, electronic devices may be connected via power cables. In some cases, it may not be possible to supply power to operate the equipment. For this reason, optical power supply converters are used that receive light transmitted to electronic devices via optical fiber cables, generate photocurrent through photoelectric conversion, and supply power.

The optical power supply converter has a semiconductor light receiving element for photoelectric conversion. The output voltage of this semiconductor photodetector is usually less than 1V. When a device receiving power from an optical power supply converter requires a high input voltage, an optical power supply converter with a high output voltage is used. For example, as in Patent Document 1, it is possible to increase the output voltage by dividing the circular light-receiving portion of a semiconductor light-receiving element into a plurality of sector-shaped photodiodes by an isolation groove and connecting these in series.

The output voltage of a semiconductor light receiving element constituted by a plurality of divided photodiodes connected in series increases as the number of photodiodes increases. On the other hand, the output current is smaller than when it is not divided, and becomes smaller as the number of divisions increases. Moreover, this output current is limited by the photodiode with the least photocurrent generated by photoelectric conversion. Therefore, in order to make the photocurrents of the plurality of photodiodes equal to each other, the circular light receiving section is equally divided so that the plurality of photodiodes have the same shape and the same area.

In order to divide the circular light receiving area into equal parts, a plurality of linear isolation grooves with a constant width are formed radially in the radial direction from the center of the circular light receiving area. Concentrate near the center. The larger the number of divisions of the circular light-receiving section, that is, the more isolation grooves there are, the closer the adjacent isolation grooves are, so that a plurality of isolation grooves are connected in the width direction at positions separated from the center of the circular light-receiving section. This makes them continuous in the circumferential direction. Since photoelectric conversion cannot be performed in the isolation groove, the more the number of divisions of the circular light-receiving area, the more isolation grooves are formed in the circumferential direction near the center of the circular light-receiving area. becomes larger.

Here, the intensity distribution of the light input through the optical fiber cable is generally a Gaussian distribution, and the light intensity decreases as the distance from the optical axis increases. This is the intensity distribution. Therefore, by allowing the optical axis of this light to pass through the center of the circular light receiving section perpendicularly to the circular light receiving section, the plurality of photodiodes of the circular light receiving section can receive the light evenly.

At this time, the high intensity part of the incident light near the optical axis enters the ineffective area near the center of the circular light receiving part and is not converted into photocurrent and is wasted, so the output of the optical power supply converter must be increased. I can't. Therefore, as in Patent Document 2, a circular photodiode is provided in the center of a circular light receiving section, and the outer circumferential side of this circular photodiode is circumferentially divided by radial isolation grooves to provide a plurality of photodiodes. , an optical power supply converter in which these photodiodes are connected in series is known.

US Patent No. 5,342,451 US Patent Application Publication No. 2011/0108081

When the circular light receiving section is divided into a circular photodiode and a plurality of photodiodes arranged in the circumferential direction around the circular photodiode as in Patent Document 2, the portion with high light intensity near the optical axis is also photoelectrically converted, and the number of divisions is reduced. The output voltage can be increased by increasing the output voltage. However, in order to equalize the photocurrent generated by multiple photodiodes, as the number of divisions of the circular photodiode increases, the diameter of the circular photodiode decreases, and the radial isolation grooves become closer to each other on the outside. so that they overlap.

Therefore, when the number of divisions of the circular light-receiving section is large, a plurality of radial isolation grooves are connected in the circumferential direction, and an ineffective area is formed to surround the circular photodiode. Therefore, a portion of the high light intensity near the optical axis will be incident on the ineffective area outside the circular photodiode, making it impossible to fully utilize the light input through the optical fiber cable. There wasn't.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a light-fed converter with improved output by improving the utilization efficiency of light from an optical fiber cable in a circular light-receiving section divided to increase output voltage.

The optical power feeding converter of the invention according to claim 1 is an optical power feeding converter that converts incident light input from an optical fiber cable into a photocurrent by a semiconductor light receiving element and outputs the photocurrent, wherein the semiconductor light receiving element includes a circular light receiving part, The circular light-receiving section has a plurality of annular isolation grooves formed along the outer periphery of the circular light-receiving section, and a plurality of annular isolation grooves formed radially with respect to the center of the circular light-receiving section. A circular photodiode in the center of the circular light-receiving section, a plurality of radial photodiodes arranged circumferentially outside the circular photodiode, and a circle partitioning the outer periphery of the circular photodiode. The plurality of radial isolation grooves are arranged in a circumferential direction outside the annular isolation groove and include one or more annular photodiodes that prevent the formation of an ineffective region in which photoelectric conversion is not possible, and the circular photodiode and the annular photodiode are connected to each other. The radial photodiode is arranged such that the light intensity decreases as the distance from the optical axis of the incident light increases, and the amount of light received is determined based on a light intensity distribution that is rotationally symmetrical with respect to the optical axis and the number of divisions of the circular light receiving section. The light-receiving area is set so that the photodiodes are equal to each other, and the circular photodiode, the annular photodiode, and the plurality of radial photodiodes are connected in series by a plurality of conductive members.

According to the above configuration, the circular light-receiving portion of the semiconductor light-receiving element has the inner side of the outer circumferential isolation groove formed along the outer periphery divided by a plurality of annular isolation grooves and a plurality of radial isolation grooves, and a circular photodetector. A diode, one or more toroidal photodiodes, and a plurality of radial photodiodes are formed. These plurality of photodiodes are connected in series. The light-receiving area of the circular photodiode, annular photodiode, and radial photodiode that this circular light-receiving section has is that the light intensity decreases as the distance from the optical axis of the incident light input from the optical fiber cable increases, and Based on the rotationally symmetrical light intensity distribution and the number of divisions of the circular light receiving section, the amounts of light received are set to be equal to each other. Therefore, variations in the photocurrent generated by the plurality of photodiodes in the circular light-receiving section are suppressed, and when these plurality of photodiodes are connected in series, the output of the semiconductor light-receiving element is reduced due to variations in the photocurrent. is suppressed. Therefore, a decrease in the output of the optical power supply converter having this semiconductor light-receiving element is suppressed. Even when the number of divisions of the circular light-receiving section is large, an ineffective area where photoelectric conversion is not possible is formed by concentrating a plurality of radial isolation grooves and connecting them in the circumferential direction on the outside of the circular photodiode in the center of the circular light-receiving section. Surrounding the circular photodiode are one or more annular photodiodes that prevent the formation of photocurrent, so that no dead area is formed where photocurrent cannot be generated. Therefore, the central part of the circular light receiving section where the light intensity of the incident light is high can be converted into photocurrent, improving the light utilization efficiency in the circular light receiving section, thereby improving the output of the optical power supply converter. can be done.

The optical power feeding converter of the invention according to claim 2 is characterized in that in the invention according to claim 1, the plurality of radial isolation grooves are formed rotationally symmetrically with respect to a central axis passing through the center of the circular light receiving section. It is said that
According to the above configuration, since the outer side of the annular photodiode is equally divided in the circumferential direction by the radial isolation grooves formed in a rotationally symmetrical manner, it is possible to easily equalize the light receiving areas of the plurality of radial photodiodes. can. Furthermore, the incident light input from the optical fiber cable has a light intensity distribution that is rotationally symmetrical with respect to the optical axis. Therefore, the optical axis of the incident light passes through the center of the circular light receiving part perpendicularly to the circular light receiving part, that is, the optical axis of the incident light is made to coincide with the central axis of the circular light receiving part. , the amount of light received by each photodiode of the circular light receiving section can be made equal to each other. Therefore, variations in the photocurrents generated by the plurality of photodiodes included in the circular light receiving section are suppressed, and a decrease in the output of the optical power supply converter can be suppressed.

According to the optically-fed converter of the present invention, it is possible to improve the efficiency of using light from the optical fiber cable in the divided circular light-receiving section to increase the output voltage, thereby improving the output of the optically-fed converter. .

1 is a perspective view of an optical power supply converter according to Example 1 of the present invention. FIG. 2 is an explanatory diagram of light incident on a semiconductor light-receiving element included in the optical power feeding converter of FIG. 1. FIG. FIG. 3 is a plan view of the semiconductor light receiving element of FIG. 2 viewed from the light incident side. 4 is a sectional view taken along the line IV-IV in FIG. 3. FIG. FIG. 2 is a light intensity distribution diagram of light input via an optical fiber cable. 7 is a graph showing an example of the diameter of a circular photodiode and the outer diameter of an annular photodiode depending on the number of divisions of a circular light receiving section. 7 is a graph showing a comparative example of output according to the division mode of the circular light-receiving section. FIG. 7 is a diagram showing another example of division of the circular light receiving section. FIG. 3 is a plan view of a back-illuminated semiconductor device according to Example 2 of the present invention, viewed from the light incident side. 10 is a sectional view taken along line XX in FIG. 9. FIG.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated based on an Example.

As shown in FIGS. 1 and 2, the optical power supply converter 1 converts light (incident light) L input via, for example, a single mode optical fiber cable OC into a photocurrent, and supplies this photocurrent to the outside. It has a pair of output terminal parts 2a and 2b for. The base 3 equipped with a pair of output terminals 2a and 2b includes a semiconductor light receiving element 10 for generating a photocurrent by photoelectric conversion from received light, and a semiconductor light receiving element 10 for protecting and shielding the semiconductor light receiving element 10. The covers 5 are fixed to each other by, for example, adhesive. A pair of electrodes 10a, 10b of the semiconductor light receiving element 10 are connected to wiring portions 3a, 3b connected to corresponding output terminal portions 2a, 2b, for example, by conductive wires 11a, 11b.

The optical fiber cable OC is inserted into an insertion hole 5a passing through the cover 5, and is fixed such that its output end E is spaced a predetermined distance from the semiconductor light receiving element 10. The cover 5 may be equipped with a positioning mechanism for the output end E of the optical fiber cable OC.

The light L input through the optical fiber cable OC is infrared light with a wavelength of, for example, about 1.5 μm. This light L is a conical beam whose irradiation range becomes wider as it advances after being emitted from the emission end E. The semiconductor light receiving element 10 has a circular light receiving section 12 that generates a photocurrent from the light L through photoelectric conversion. The optical axis OA of the light L emitted from the output end E passes through the center C of the circular light receiving section 12 perpendicularly to the circular light receiving section 12, that is, the optical axis OA and the central axis of the circular light receiving section 12 coincide. The output end E is positioned so that the output end E is positioned as shown in FIG.

As shown in FIG. 3, the circular light-receiving section 12 includes, for example, a circular PIN-type photodiode provided with a light absorption layer, which is divided into a plurality of photodiodes by an isolation groove of a constant width, and these plurality of photodiodes are connected in series. is connected to and formed. Note that since no photocurrent is generated in the isolation groove, it is preferable to reduce the area of the isolation groove in the area of the circular light receiving section 12 in order to increase the output.

A circular photodiode 14 a is formed in the center of the circular light receiving section 12 by a first annular isolation groove 13 a concentric with the circular light receiving section 12 . Further, between the first annular isolation groove 13a and the second annular isolation groove 13b which is concentric with the circular light receiving part 12 and has a diameter larger than the first annular isolation groove 13a, an annular photodiode 14b is provided. It is formed.

Between the second annular isolation groove 13b and the outer periphery isolation groove 13n formed along the outer periphery of the circular light receiving part 12, a plurality of grooves (in this case, 30 A straight radial isolation groove 15 is formed. These plurality of radial isolation grooves 15 are formed rotationally symmetrically with respect to the central axis passing through the center C of the circular light receiving section 12, and equally divide the outside of the annular photodiode 14b in the circumferential direction. The annular isolation groove 13b and the outer circumferential isolation groove 13n are connected. Note that in FIG. 3, some of the symbols of the radial isolation grooves 15 are omitted.

In this way, a plurality of (30 in this case) radial photodiodes 16 are formed by a plurality of radial isolation grooves 15 on the outside of the annular photodiode 14b. These radial photodiodes 16 are arranged in the circumferential direction so as to surround the annular photodiode 14b. Hereinafter, the circular, annular, and radial photodiodes formed by dividing the circular light receiving section 12 may be referred to as PD without distinction. Note that in FIG. 3, some of the symbols of the radial photodiodes 16 are omitted.

Each PD (circular photodiode 14a, annular photodiode 14b, and radial photodiode 16) of the circular light receiving section 12 is an n-type semiconductor layer stacked on a semi-insulating semiconductor substrate 20, as shown in FIG. 4, for example. 21, a light absorption layer 22, and a p-type semiconductor layer 23. The semiconductor substrate 20 is, for example, an InP substrate, the n-type semiconductor layer 21 is, for example, an n-InP layer, the light absorption layer 22 is, for example, an InGaAs layer, and the p-type semiconductor layer 23 is, for example, a p-InP layer. The circular light receiving section 12 is not limited to this, and the circular light receiving section 12 is not limited to the PIN type. Note that the thicknesses of the n-type semiconductor layer 21, the light absorption layer 22, and the p-type semiconductor layer 23 can be set as appropriate, and are often formed to a thickness of about 0.5 to 10 μm.

The isolation grooves (first and second annular isolation grooves 13a, 13b, outer circumferential isolation groove 13n, and multiple radial isolation grooves 15) include an n-type semiconductor layer 21, a light absorption layer 22, and a p-type semiconductor layer 23. It is formed by selectively etching the semiconductor substrate 20 on which are stacked layers from the p-type semiconductor layer 23 side until the semiconductor substrate 20 is reached. This forms a plurality of electrically isolated PDs. Note that the sidewalls of the isolation groove may be inclined such that, for example, the width becomes narrower toward the semiconductor substrate 20 side.

Each of the plurality of PDs has a through hole 17 that penetrates the p-type semiconductor layer 23 and the light absorption layer 22 and reaches the n-type semiconductor layer 21 . An insulating protective film 24 is formed to cover the surfaces of the plurality of PDs and the inner walls of the through holes 17 of these PDs, and to fill the isolation grooves. The protective film 24 preferably has an anti-reflection function for the incident light L, but an anti-reflection film not shown may be formed.

In each PD, the protective film 24 on the p-type semiconductor layer 23 and inside the through-hole 17 is partially removed, and the n-type semiconductor layer 21 is exposed at the p-type semiconductor layer 23 and the bottom of the through-hole 17 . As shown in FIGS. 3 and 4, in order to connect a plurality of PDs in series using a plurality of conductive members 25, one exposed p-type semiconductor layer 23 is placed between adjacent PDs via an isolation groove. and the other n-type semiconductor layer 21 are connected by a conductive member 25. Note that in FIG. 3, some of the symbols of the plurality of conductive members 25 are omitted.

The conductive member 25 is formed by selectively depositing a metal laminated film using, for example, a lift-off method. The metal laminated film is composed of an adhesion layer such as titanium or chromium, and a low resistivity layer such as gold, silver, or aluminum. Since the isolation groove is filled with the protective film 24 and the step difference is reduced, the formation of the conductive member 25 is facilitated.

Further, on the protective film 24 in which the radial isolation groove 15 is embedded, conductive members 25 are provided, for example, for connecting the electrode 10a and the circular photodiode 14a and for connecting the annular photodiode 14b and the radial photodiode 16, respectively. is formed so that the incident light L is not blocked. Since the conductive members 25 connecting adjacent radial photodiodes 16 are formed rotationally symmetrically with respect to the central axis passing through the center C of the circular light receiving section 12, each radial photodiode 16 is shielded by the conductive member 25. It is preferable that the amounts of light emitted are equal.

When the isolation groove is filled with the protective film 24 and there is no step, a plurality of conductive members 25 can be easily formed. The isolation groove may be filled with the protective film 24 by making the level difference small to the extent that the conductive member 25 can be formed. Although not shown, an anode electrode connected to the p-type semiconductor layer 23 and a cathode electrode connected to the n-type semiconductor layer 21 are formed in each PD, and one anode electrode is connected to the other between adjacent PDs in the same manner as described above. It may be connected to the cathode electrode by a conductive member 25. Further, as the conductive member 25, for example, a conductive wire containing gold as a main component may be used.

In the circular light receiving section 12, since the circular photodiode 14a, the annular photodiode 14b, and the plurality of radial photodiodes 16 are connected in series, the photocurrent output by the semiconductor light receiving element 10 is small, but the output voltage is It can be made higher. Therefore, the optical power supply converter 1 equipped with the semiconductor light receiving element 10 for photoelectrically converting light input via the optical fiber cable OC can supply power at a high voltage.

The light L emitted from the output end E of the optical fiber cable OC spreads into a conical shape with an apex angle θ (full angle) of 14 degrees, for example, as shown in FIGS. 2 and 5, and enters the circular light receiving portion 12. The light intensity distribution of this light L is a Gaussian distribution, and the light intensity decreases as the distance from the optical axis OA increases, and the light intensity distribution becomes rotationally symmetrical with respect to the optical axis OA. Based on this light intensity distribution, the circular photodiode 14a, the annular photodiode 14b, and the radial photodiode 16 The light-receiving area of each is set. The circular photodiode 14a that receives high-intensity light has a small area, and the radial photodiode 16 that receives low-intensity light has a larger area than the circular photodiode 14a and the annular photodiode 14b. The light receiving area is such that, for example, the light intensity incident on the outermost portion of the circular light receiving section 12 is 1/ ^e2 of the light intensity incident on the center C (approximately 90% of the light L is irradiated onto the circular light receiving section 12). ), the amount of light received by each PD is set to be equal to each other.

When the optical input is constant, the photocurrent that each PD can generate varies depending on the number of PDs that the circular light receiving section 12 has. Therefore, when the light receiving area is set so that the photocurrent generated by each PD is equal based on the light intensity distribution, the diameter and circle of the circular photodiode 14a are determined according to the number of PDs that the circular light receiving section 12 has. The outer diameter of the annular photodiode 14b is set.

For example, FIG. 6 shows a case where a circular light receiving section 12 with a diameter D0=1 mm is divided into one circular photodiode 14a, one annular photodiode 14b, and a plurality of radial photodiodes 16 by an isolation groove with a width of 10 μm. An example of setting the diameter D1 of the circular photodiode 14a and the outer diameter D2 of the annular photodiode 14b is shown in FIG.

When the circular light receiving section 12 is divided into 10 PDs and has one circular photodiode 14a, one annular photodiode 14b, and eight radial photodiodes 16, the diameter D1 of the circular photodiode 14a is 230 μm. , the outer diameter D2 of the annular photodiode 14b is set to 340 μm. Further, when the circular light receiving section 12 is divided into 32 PDs and has one circular photodiode 14a, one annular photodiode 14b, and 30 radial photodiodes 16 (see FIG. 3), the circular photodiode The diameter D1 of the diode 14a is set to 126 μm, and the outer diameter D2 of the annular photodiode 14b is set to 179 μm. Note that the diameter D0 of the circular light receiving section 12, the number of PDs, and the width of the isolation groove can be set as appropriate.

FIG. 7 shows the relative output for each division pattern, assuming that the output (power) of pattern #1 in which the circular light receiving portion 12 with a diameter D0 = 1 mm is not divided is 1. In pattern #2, the circular light receiving section is radially divided into 30 equal parts by a plurality of linear isolation grooves extending radially from the center of the circular light receiving section. In this pattern #2, an ineffective region where photoelectric conversion cannot be performed is formed near the center of the circular light receiving section 12 where a plurality of isolation grooves are concentrated, and the relative output is 0.89. In other words, in pattern #2, the utilization efficiency of light incident on the circular light receiving section 12 is 11% lower than in pattern #1, and there is a large waste of light input.

In pattern #3, a circular photodiode with a diameter of 128 μm is provided concentrically with the circular photodiode at the center of the circular photodiode, and 30 radial photodiodes are provided by dividing the circumference of the circular photodiode into 30 equal parts. The circular photodiode reduces the ineffective area compared to pattern #2, and the relative output of pattern #3 is 0.93. Pattern #3 has improved utilization efficiency of light incident on the circular light receiving section 12 compared to pattern #2.

In pattern #4, which corresponds to the circular light receiving section 12 in FIG. 3, a circular photodiode with a diameter of 126 μm and an annular photodiode with an outer diameter of 179 μm are provided in the center of the circular light receiving section concentrically with the circular light receiving section. , the outside of the annular photodiode is divided into 30 equal parts to provide 30 radial photodiodes. In this pattern #4, an ineffective region that should be formed by concentration of isolation grooves outside the circular photodiode is not formed by the annular photodiode. Therefore, the relative output of pattern #4 is 0.97, and the output can be made larger than patterns #2 and #3. Therefore, in pattern #4, the utilization efficiency of light incident on the circular light receiving portion 12 is improved compared to pattern #3, and the wasted light input is reduced compared to patterns #2 and #3.

As shown in FIG. 6, as the number of PDs included in the circular light receiving section 12 increases, the outer diameter D2 of the annular photodiode 14b becomes smaller, so that a plurality of radial isolation grooves 15 are concentrated near the annular photodiode 14b. I come to do it. Therefore, on the outside of the annular photodiode 14b, not only the second annular isolation groove 13b but also a plurality of radial isolation grooves 15 are connected in the width direction, and are connected in the circumferential direction. A region will be formed.

In order to prevent the formation of such an ineffective area, for example, as shown in FIG. 8, the circular light receiving section 12 has a second circular isolation groove 13b and a third circular isolation groove on the outside of the circular photodiode 14b. A second annular photodiode 14c may be formed between the photodiodes 13c and 13c. Also in this case, the photocurrents generated by the plurality of PDs (circular photodiode 14a, two annular photodiodes 14b, 14c, and plurality of radial photodiodes 16) of the circular light receiving section 12 are input so that they are equal to each other. The light receiving area of each PD is set based on the light intensity distribution of the light L. The circular light receiving section 12 may include three or more annular photodiodes. Note that in FIG. 8, some of the symbols of the radial isolation grooves 15 and the symbols of the radial photodiodes 16 are omitted.

Although not shown, even when the number of annular photodiodes is increased, the plurality of PDs of the circular light receiving section 12 are connected in series by the plurality of conductive members 25. As described above, even when the circular light-receiving section 12 has a large number of PDs, the circular photodiode and one or more annular photodiodes prevent the formation of an ineffective area and utilize the light incident on the circular light-receiving section 12. Efficiency can be increased.

The optical power supply converter 1 can be constructed using a back-illuminated semiconductor light-receiving element 10A as shown in FIGS. 9 and 10 instead of the semiconductor light-receiving element 10. The back-illuminated semiconductor light-receiving device 10A has a structure in which a part of the semiconductor light-receiving device 10 is modified, and parts common to the semiconductor light-receiving device 10 are designated by the same reference numerals, and a description thereof will be omitted.

The semiconductor substrate 20 of the semiconductor light receiving element 10A is made of a material that is transparent to incident light, and transmits the incident light L without absorbing it. For example, an InP substrate is transparent to infrared light having a wavelength of approximately 1 μm or more. Preferably, an antireflection film 26 for suppressing reflection of the light L is formed on the light L incident surface (back surface) of the semiconductor substrate 20. The circular light receiving section 12 is divided by isolation grooves as described above, and has a plurality of PDs (a circular photodiode 14a, an annular photodiode 14b, and a plurality of radial photodiodes 16).

The light receiving area of each of the plurality of PDs is set based on the light intensity distribution of the incident light L in the same way as described above so that the amount of light received is equal to each other. These plurality of PDs each include an anode electrode 27 connected to the p-type semiconductor layer 23 and a cathode electrode 28 connected to the n-type semiconductor layer 21. Note that in FIG. 9, some of the symbols of the radial photodiodes 16 are omitted.

The anode electrode 27 of one of the adjacent PDs and the cathode electrode 28 of the other are connected so that the plurality of PDs of the circular light receiving section 12 are connected in series by the plurality of conductive members 4 formed on the base 3. It is fixed to a corresponding conductive member 4 with, for example, conductive paste 6. Although not shown, in order to output the photocurrent generated in the circular light receiving section 12 from the output terminal sections 2a and 2b, a wiring section 3a corresponding to the conductive members 4 at both ends of a plurality of PDs connected in series. , 3b. Since the plurality of conductive members 4 do not block the light L incident on the circular light receiving section 12, variations in photocurrent among the plurality of PDs can be further reduced.

The operation and effects of the optical power feeding converter 1 will be explained.
The optical power supply converter 1 converts the incident light L input from the optical fiber cable OC into a photocurrent using the semiconductor light receiving elements 10 and 10A, and outputs the photocurrent. The semiconductor light-receiving elements 10 and 10A have a circular light-receiving section 12 that generates a photocurrent through photoelectric conversion. The circular light receiving section 12 has a plurality of annular isolation grooves 13a, 13b concentric with the circular light receiving section 12 and a plurality of radial isolation grooves 15 on the inside of an outer circumferential isolation groove 13n formed along the outer periphery of the circular light receiving section 12. It is divided. As a result, the circular light receiving section 12 includes a circular photodiode 14a at the center, a plurality of radial photodiodes 16 arranged in the circumferential direction on the outside thereof, and an annular isolation groove 13a on the outside of the annular isolation groove 13a that partitions the outer periphery of the circular photodiode 14a. One or more annular photodiodes 14b are formed in order to prevent the formation of an ineffective region in which photoelectric conversion is not possible, where the plurality of radial isolation grooves 15 are continuous in the circumferential direction. The light-receiving areas of the circular photodiode 14a, the annular photodiode 14b, and the radial photodiode 16 are each set so that the amount of light received is equal to each other based on the light intensity distribution of the incident light and the number of divisions of the circular light-receiving section. A plurality of conductive members 25 and 4 are connected in series.

Since the amounts of light received by the plurality of photodiodes included in the circular light receiving section 12 are equal to each other, variations in photocurrent generated by these photodiodes can be reduced. Therefore, the circular light receiving section 12 in which these photodiodes are connected in series can prevent the output from decreasing due to the photodiode generating a small photocurrent. Therefore, it is possible to prevent a decrease in the output of the optical power supply converter 1 that supplies power to the outside from the semiconductor light receiving elements 10, 10A having the circular light receiving section 12. Further, although no photocurrent is generated in the annular and radial isolation grooves, the portions where the light intensity of the incident light is high are generated by the circular photodiode 14a and the annular photodiode 14b formed at the center of the circular light receiving section 12. This can prevent the photocurrent from being wasted without being converted into photocurrent.

The plurality of radial isolation grooves 15 are formed rotationally symmetrically with respect to a central axis passing through the center C of the circular light receiving section 12. Since the outer side of the annular photodiode 14b is equally divided in the circumferential direction of the circular light receiving section 12 by the plurality of radial isolation grooves 15, the light receiving area of the plurality of radial photodiodes 16 can be easily made equal. Since the incident light input from the optical fiber cable OC has a light intensity distribution that is rotationally symmetrical with respect to the optical axis OA, by making the incident light enter so that the optical axis OA passes through the center C of the circular light receiving part 12, The amount of light received by the photodiode 14a, the annular photodiode 14b, and each radial photodiode 16 can be made equal to each other. Therefore, it is possible to reduce variations in the photocurrents generated by these photodiodes and prevent a decrease in the output of the optical power supply converter 1.

In addition, those skilled in the art can implement various modifications to the above-described embodiments without departing from the spirit of the present invention, and the present invention includes such modifications.

1: Optical power supply converter 2a, 2b: Output terminal section 3: Base 4: Conductive member 5: Cover 5a: Insertion hole 10, 10A: Semiconductor light receiving element 10a, 10b: Electrode 11a, 11b: Conductive wire 12: Circular Light receiving parts 13a to 13c: first to third annular isolation grooves (annular isolation grooves)
13n: Outer periphery isolation groove 14a: Circular photodiode 14b: Annular photodiode 14c: Second annular photodiode 15: Radial isolation groove 16: Radial photodiode 17: Through hole 20: Semiconductor substrate 21: N-type semiconductor Layer 22: Light absorption layer 23: P-type semiconductor layer 24: Protective film 25: Conductive member 26: Anti-reflection film 27: Anode electrode 28: Cathode electrode OC: Optical fiber cable E: Output end L: Light (incident light)

Claims (2)

In an optical power supply converter that converts incident light input from an optical fiber cable into a photocurrent using a semiconductor photodetector and outputs it,
The semiconductor light-receiving element includes a circular light-receiving section,
The circular light-receiving section has an outer peripheral isolation groove formed along its outer periphery, and an inner side thereof is formed radially with respect to a plurality of annular isolation grooves concentric with the circular light-receiving section and a center of the circular light-receiving section. A plurality of radial isolation grooves partition the circular photodiode at the center of the circular light-receiving section, a plurality of radial photodiodes arranged circumferentially outside the circular photodiode, and an outer periphery of the circular photodiode. one or more annular photodiodes that prevent the formation of an ineffective region in which photoelectric conversion is not possible, where the plurality of radial isolation grooves are connected in the circumferential direction outside the annular isolation groove;
The circular photodiode, the annular photodiode, and the radial photodiode each have a light intensity distribution in which the light intensity decreases as the distance from the optical axis of the incident light increases, and the light intensity distribution is rotationally symmetrical with respect to the optical axis, and the circular light receiving The light receiving area is set so that the amount of light received is equal to each other based on the number of divisions of the parts,
An optical power supply converter characterized in that the circular photodiode, the annular photodiode, and a plurality of the radial photodiodes are connected in series by a plurality of conductive members. 2. The optical power supply converter according to claim 1, wherein the plurality of radial photodiodes are formed rotationally symmetrically with respect to a central axis passing through the center of the circular light receiving section.

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