JP5376518B2 - Optical terminal unit and optical transmission system - Google Patents

Description

  The present invention relates to an optical terminal unit for receiving an optical signal transmitted through an optical fiber, and an optical transmission system including the optical terminal unit.

  For example, Japanese Unexamined Patent Application Publication No. 2007-158669 (Patent Document 1) discloses an optical terminal unit that can be reduced in cost while having a simplified configuration. This optical terminal unit includes a photodiode and a high-frequency transformer. The non-biased photodiode receives an optical signal transmitted by the optical fiber and generates a voltage corresponding to the optical signal. The high-frequency transformer is connected between both ends of the photodiode and generates an output corresponding to the voltage generated by the photodiode. According to this configuration, since it is not necessary to put the photodiode in a reverse bias state, the configuration of the optical terminal unit can be simplified and the cost of the optical terminal unit can be reduced.

JP 2007-158669 A

  The non-powered optical receiver such as the optical terminal unit described above is applied to, for example, an FTTH (Fiber To The Home) terminal having a small number of analog channels and a large number of digital channels.

  In the future, the use of broadband and multi-channel optical transmission is expected to increase. In order to realize broadband and multi-channel optical transmission, it is preferable that the optical receiver has good distortion performance. However, according to the configuration of the optical receiver described above, it is not easy to improve the distortion performance because the photodiode operates in a non-biased state.

  As a method for improving the distortion performance, a method of applying a reverse bias voltage to the photodiode can be considered. However, according to the above configuration, a power source for applying a reverse bias voltage to the photodiode is required.

  FIG. 9 is a diagram for explaining the configuration of an optical transmission system provided with a conventional optical terminal device 101. Referring to FIG. 9, optical terminal apparatus 101 is used in, for example, a joint reception facility. The head-end device includes a transmission device composed of a plurality of devices that receive various broadcast signals with an antenna or the like and transmit them at an appropriate level, or perform modulation conversion and transmit them at an appropriate level. For example, the head end device includes an FM broadcast transmission device 51, an analog broadcast transmission device 52, a terrestrial digital broadcast transmission device 53, a CATV digital broadcast transmission device 54, a BS digital broadcast transmission device 55, and a 110-degree CS digital broadcast transmission. Device 56. The head end device further includes a mixer 57, an optical transmitter 58, an optical amplifier 59, and an optical splitter 60.

  Each sending device includes an amplifier for amplifying the received broadcast signal. The mixer 57 mixes and outputs the signal output from the amplifier of each sending device. The optical transmitter 58 generates an optical signal based on the signal (electric signal) output from the mixer 57 and outputs the optical signal. The optical amplifier 59 amplifies the optical signal from the optical transmitter 58. The optical branching device 60 distributes the optical signal from the optical amplifier 59. The optical signal from the optical amplifier 59 is sent to the optical fiber 61 through the optical branching device 60.

  An optical distributor, specifically, a closure 62 is provided in the middle of the optical fiber 61. The closure 62 distributes the optical signal transmitted through the optical fiber 61. The optical signal distributed by the closure 62 is transmitted by the optical fiber 61 to the subscriber's home where the optical terminal device 101 is provided.

  The optical terminal device 101 is configured to be capable of outputting two systems. In one system, a photoelectric conversion unit that photoelectrically converts an optical signal into an electric signal at the time of power supply and no power supply, and a signal processing circuit that processes an electric signal photoelectrically converted from the optical signal by the photoelectric conversion unit are built in. Is supplied to the FM notification broadcasting terminal 3 via a coaxial cable. In the other system, in order to improve the distortion performance in the broadband transmission, a signal processing circuit that operates by feeding is provided after the photoelectric conversion unit, and an electric signal output from this system is supplied to the distributor 5. The distributor 5 distributes and supplies the supplied signal to the television receiver 6.

  An object of the present invention is to provide an optical terminal unit capable of obtaining good distortion performance while eliminating the need for external power supply, and an optical transmission system including the optical terminal unit.

  In summary, the present invention provides an optical terminal unit, a signal generator for generating first and second optical signals from an optical signal transmitted by an optical fiber, a first anode and a grounded first A first photodiode having one cathode, a second anode grounded, and a second photodiode having a second cathode. The first photodiode generates a photocurrent by photoelectrically converting the first optical signal, and outputs the photocurrent from the first anode. The second photodiode is in a state in which photocurrent is supplied from the first anode of the first photodiode to the second cathode, and the second photodiode is in a state in which a reverse bias is applied. With the reverse bias applied in this way, the second photodiode converts the second optical signal into an electrical signal and outputs the electrical signal from the second cathode or the second anode.

  Preferably, the optical terminal unit is provided between the first cathode and the ground node, and is provided between the first filter that prevents transmission of a high-frequency component, and the first anode and the second cathode. And a second filter for blocking the transmission of the high frequency component, a third filter provided between the second anode and the ground node, for blocking the transmission of the high frequency component, and an output terminal. The output terminal is provided between any one of the second cathode and the second filter and between the second anode and the third filter. From the second anode or the second cathode, the output terminal is provided. The output electric signal is output to the outside of the optical terminal unit.

  Preferably, the signal generation unit includes an optical branching device that branches the input optical signal into first and second optical signals.

  Preferably, the optical signal input to the signal generation unit is a signal in which a plurality of optical signals having different wavelengths are multiplexed. The signal generation unit includes an optical demultiplexer that generates the first and second optical signals by separating the input optical signal according to the difference in wavelength.

  In another aspect, the present invention is an optical transmission system, which is a signal transmission device that transmits an optical broadcast signal, an optical fiber that transmits an optical broadcast signal transmitted from the signal transmission device, and an optical fiber. And an optical terminal unit to which an optical broadcast signal is supplied, and a terminal device that receives an electrical signal output from the optical terminal unit.

  ADVANTAGE OF THE INVENTION According to this invention, the optical terminal unit which has favorable distortion performance is realized, making the external electric power feeding unnecessary.

It is a figure explaining the structure of the optical transmission system provided with the optical terminal unit which concerns on embodiment of this invention. It is a conceptual diagram which shows the structure of the optical terminal unit 2 which concerns on embodiment of this invention. It is a block diagram for demonstrating in detail the structure of the optical terminal unit 2 shown in FIG. It is a circuit diagram for demonstrating the specific structural example of the optical terminal unit 2 shown in FIG. It is the figure which showed the comparative example of the optical terminal unit which concerns on embodiment of this invention. It is the figure which showed concretely the distortion performance of the 2nd comparative example of the optical terminal unit of FIG. 4 (A) which concerns on embodiment of this invention, and the optical terminal unit shown to FIG. 5 (B). It is the figure which showed the example of the external appearance of the optical terminal unit 2 which concerns on embodiment of this invention. It is the figure explaining other structures of the optical terminal unit which concerns on embodiment of this invention. It is a figure for demonstrating the structure of the optical transmission system provided with the conventional optical terminal device 101. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a diagram illustrating a configuration of an optical transmission system including an optical terminal unit according to an embodiment of the present invention.

  Referring to FIG. 1, an optical terminal unit 2 according to an embodiment of the present invention is used in, for example, a joint reception facility. In this joint reception facility, the head-end device includes a transmission device composed of a plurality of devices that receive various broadcast signals with an antenna and transmit them at an appropriate level, or perform modulation conversion and transmit at an appropriate level. . Specifically, the head end device includes an FM broadcast transmission device 51, an analog broadcast transmission device 52, a terrestrial digital broadcast transmission device 53, a CATV digital broadcast transmission device 54, a BS digital broadcast transmission device 55, and 110 degrees. CS digital broadcast transmission device 56.

  The head end device further includes a mixer 57, an optical transmitter 58, an optical amplifier 59, and an optical splitter 60.

  Each sending device includes an amplifier for amplifying the received broadcast signal. The mixer 57 mixes and outputs the signal output from the amplifier of each sending device. The optical transmitter 58 generates an optical signal based on the signal (electric signal) output from the mixer 57 and outputs the optical signal. The optical amplifier 59 amplifies the optical signal from the optical transmitter 58. The optical branching device 60 distributes the optical signal from the optical amplifier 59. The optical signal from the optical amplifier 59 is sent to the optical fiber 61 through the optical branching device 60. For example, the wavelength band of the optical signal is a 1.55 μm band.

  An optical distributor, specifically, a closure 62 is provided in the middle of the optical fiber 61. The closure 62 distributes the optical signal transmitted through the optical fiber 61. The optical signal distributed by the closure 62 is transmitted by the optical fiber 61 to the subscriber's home provided with the optical terminal device. In the optical transmission system shown in FIG. 1, the optical fiber 61 is provided not only in the broadcasting system signal transmitted from the transmission device provided in the head end device as an optical signal but also in the head end device. A communication signal transmitted from a communication optical transmitter (not shown) is transmitted as an optical signal.

  In addition to the optical terminal unit 2 that is a broadcast V-ONU, a communication D-ONU (not shown) is provided inside the optical terminal device 1 at the subscriber's home. The optical terminal unit 2 receives an optical signal via the optical fiber 61. The optical terminal unit 2 converts an optical signal into an electric signal (RF signal) by a photoelectric conversion unit, and supplies the RF signal to a terminal device. The D-ONU receives an optical signal via an optical fiber 61 by a communication optical transmitter (not shown) provided in the head end device, and the optical signal is converted into an electrical signal (communication signal) by a photoelectric conversion unit. And transmitted to a personal computer or the like in the subscriber's home via a LAN cable (not shown).

  The optical terminal unit 2 has two outputs. The output 2 a of the optical terminal unit is connected to the FM notification broadcast terminal 3. The output 2b of the optical terminal unit is connected to the digital receiver 4. The FM notification broadcast terminal 3 receives a general notification broadcast informing life information and the like and an emergency broadcast at the time of a disaster, and outputs the received content as an audio signal.

  The digital receiver 4 receives terrestrial digital broadcast, CATV digital broadcast, BS digital broadcast, and 110 degree CS digital broadcast. The digital receiver 4 is composed of, for example, a set top box and a television.

  FIG. 2 is a conceptual diagram showing a configuration of the optical terminal unit 2 according to the embodiment of the present invention. Referring to FIG. 2, the optical terminal unit 2 includes a connector 20, an optical branching unit 21 that is a signal generation unit, a power generation unit 22, an RF (Radio Frequency) conversion unit 23 that is a photoelectric conversion unit, and an output terminal. And a connector 24.

Connector 20 is connected to an optical fiber (not shown), receives the optical signal S ₀ from the optical fiber. The optical branching device 21 branches the optical signal S ₀ input via the connector 20 into optical signals S ₁ and S ₂ . That is, the original optical signal S ₀ is divided into _two optical signals S ₁ and S ₂ by the optical branching device 21. By the above method, the optical branching device 21 which is a signal generation unit generates the optical signals S ₁ and S ₂ from the optical signal S ₀ .

The power generation unit 22 generates power (photocurrent) from the optical signal S ₁ from the optical branching device 21 and supplies the power to the RF conversion unit 23 that is a photoelectric conversion unit. RF converter 23 converts the optical signal _{S 2} from the optical divider 21 into an electric signal Se (high frequency signal).

The connector 24 is connected to, for example, a coaxial cable having an F-type plug attached to the tip thereof. The electrical signal Se converted from the optical signal S ₂ by the RF conversion unit 23 is sent to the connector 24 and sent to the coaxial cable via the connector 24. The electric signal Se transmitted to the coaxial cable is sent to various terminal devices shown in FIG. That connector 24 is for outputting the electrical signal Se that has been converted from the optical signal S ₂ by the RF converter 23 to the outside of the optical terminal unit 2.

  In the case where the terminal unit 2 according to the embodiment of the present invention is applied to the optical transmission system shown in FIG. 1, in order to correspond to the two-system output, one branching device or two distributors are provided at the subsequent stage of the connector 24. 2 outputs.

  FIG. 3 is a block diagram for explaining the configuration of the optical terminal unit 2 shown in FIG. 2 in more detail. Referring to FIGS. 3 and 2, power generation unit 22 and RF conversion unit 23 are configured by photodiodes (PD). The optical terminal unit 2 further includes filters 25, 26 and 27. Each of the filters 25, 26, and 27 is a filter for preventing transmission (inflow and outflow) of high-frequency noise in a wide band.

The power generation unit 22 is provided between the ground node 35 and the RF conversion unit 23. One end 31 of power generation unit 22 is electrically connected to ground node 35 through filter 25. Thereby, the electric potential of the one end 31 of the electric power generation part 22 can be stabilized. The other end 32 of the power generation unit 22 is electrically connected to the RF conversion unit 23 via the filter 26. The filter 26 removes fluctuation components (high-frequency components) included in the power P (photocurrent) from the power generation unit 22 (photodiode) in order to stabilize the power P (photocurrent). Thereby, a substantially constant power, that is, a photocurrent is supplied to the RF conversion unit 23. In a condition in which the light current is fed to the RF converter 23, RF converter 23 is photoelectrically converting an optical signal S ₂ to an electrical signal Se. The “one end 31” and the “other end 32” correspond to the cathode and anode of the photodiode, respectively.

  One end 33 of the RF conversion unit 23 is electrically connected to the filter 26 in order to receive power (photocurrent) from the power generation unit 22. On the other hand, the other end 34 of the RF conversion unit 23 is electrically connected to the connector 24 and is also electrically connected to the ground node 35 via the filter 27. Thereby, the electric potential of the other end 34 of the RF converter 23 can be stabilized. The “one end 33” and the “other end 34” correspond to the cathode and anode of the photodiode, respectively.

In the configuration shown in FIG. 3, the RF conversion unit 23 converts the optical signal S ₂ into an electrical signal Se, and supplies the electrical signal Se to the connector 24 between the other end 34 of the RF conversion unit 23 and the filter 27. . Although not shown in FIG. 3, the connector 24 is connected between one end 33 of the RF conversion unit 23 and the filter 26, and an electric signal Se is supplied from the one end 33 of the RF conversion unit 23 to the connector 24. You may do it.

  FIG. 4 is a circuit diagram for explaining a specific configuration example of the optical terminal unit 2 shown in FIG. Referring to FIG. 4A and FIG. 3, filter 25 includes a coil 25a and a capacitor 25b. One end of the coil 25a is connected to the cathode of the photodiode, which is one end 31 of the power generation unit 22, and one end of the capacitor 25b. The other end of coil 25 a is connected to ground node 35. The filter 26 includes a coil 26a and capacitors 26b and 26c. One end of the coil 26 a is connected to the anode of the photodiode, which is the other end 32 of the power generation unit 22, and one end of the capacitor 26 b. The other end of the coil 26 a is connected to the cathode of the photodiode, which is one end 33 of the RF converter 23, and one end of the capacitor 26 c.

  The filter 27 includes a coil 27a, a resistor 27b, and a capacitor 27c. The coil 27 a and the resistor 27 b are connected in series between the anode of the photodiode that is the other end 34 of the RF conversion unit 23 and the ground node 35. The capacitor 27c is connected in parallel with the resistor 27b.

The photodiode as the power generation unit 22 generates power P (photocurrent) to be supplied to the RF conversion unit 23 and outputs the power P (photocurrent) from the anode. The photodiode as RF converter 23, becomes the same state as the state where a reverse bias is applied by receiving power P (light current) to the cathode converts the optical signal S ₂ to an electrical signal Se, the electric signal Se is output from the anode through the capacitor 28.

  In addition, as shown in FIG. 4B, the electric signal Se can be output from the cathode of the photodiode. In this case, one end of the capacitor 26c is connected to the anode of the photodiode, and the other end of the capacitor 26c is grounded. Further, the capacitor 28 and the output terminal 24 are connected to the cathode side of the photodiode.

  Since the optical terminal unit 2 has the above configuration, the distortion performance can be improved. This point will be described by comparing the embodiment of the present invention and its comparative example.

  FIG. 5 is a diagram showing a comparative example of the optical terminal unit according to the embodiment of the present invention. FIG. 5A is a diagram showing a first comparative example, and FIG. 5B is a diagram showing a second comparative example.

Referring to FIG. 5A, one end 33 of RF conversion unit 23 is connected to power supply node 36 and receives voltage VCC from power supply node 36. The other end 34 of the RF conversion unit 23 is connected to the ground node 35 via the filter 27. The RF conversion unit 23 converts the optical signal S ₀ into an electrical signal Se, and supplies the electrical signal Se to the connector 24 from between the other end 24 of the RF conversion unit 23 and the filter 27.

  The photodiode which is the RF conversion unit 23 is configured to be in a reverse bias state when supplied with a photocurrent. When the photodiode is in a reverse bias state, the distortion performance of the photodiode is improved. However, since the voltage VCC must be constantly supplied to the RF conversion unit 23, a separate power source is required. Furthermore, when a power failure occurs, the optical terminal unit becomes inoperable.

  Referring to FIG. 5B, one end 33 of RF conversion unit 23 is connected to ground node 35. Similarly, the other end 34 of the RF conversion unit 23 is connected to the ground node 35 via the filter 27, and an electric signal Se is supplied to the connector 24 from between the other end 34 of the RF conversion unit 23 and the filter 27. . In this case, it is not necessary to supply power to the photodiode that is the RF conversion unit 23. However, since the photodiode is operated in a non-biased state, its distortion performance is in a state of deterioration as compared with the distortion performance in the case of the configuration shown in FIG.

On the other hand, according to the embodiment of the present invention, the optical splitter 21 generates _two optical signals S ₁ and S ₂ from one optical signal S ₀ . The optical signal S ₁ is converted into electric power (photocurrent) by the electric power generation unit 22. The photocurrent is supplied to the RF conversion unit 23. RF converter 23, in a state of receiving the photocurrent from the power generating unit 22, converts the optical signal S ₂ to an electrical signal Se. Since the photocurrent is supplied to the RF converter 23 by the optical divider 21 inputs the optical signals S _0, photodiode reverse bias state is a RF converter 23 supplies a photocurrent (RF converter 23 There is no need to provide a separate power source. Further, the optical signal is converted into an electric signal by the RF converter 23 (photodiode in the reverse bias state) supplied with the photocurrent. By applying a reverse bias to the photodiode, it is possible to increase the response speed, so that a good distortion performance can be obtained over a wide band of the RF signal.

  Therefore, according to the embodiment of the present invention, it is possible to realize an optical terminal unit capable of obtaining good distortion performance while eliminating the need for external power supply. Furthermore, according to the embodiment of the present invention, since the optical transmission system includes the above-described optical terminal unit, it is possible to realize an optical transmission system that can obtain good distortion performance on the terminal side.

  FIG. 6 is a diagram specifically showing the distortion performance between the optical terminal unit of FIG. 4A and the second comparative example of the optical terminal unit shown in FIG. 5B according to the embodiment of the present invention. It is. Referring to FIG. 6, the horizontal axis of the graph represents frequency (unit: MHz), and the vertical axis of the graph represents composite secondary distortion (CSO; unit dB). The greater the absolute value of CSO in FIG. 6, the better the distortion performance.

  In the optical terminal unit 2 according to the embodiment of the present invention shown in FIG. 4 (A), the broken line A has an input level of −2 (dBm) of the optical signal to the optical terminal unit 2 and the RF conversion unit 23. Fig. 5 shows the frequency characteristics of CSO in a state where photocurrent is supplied from the power generation unit 22.

  In the second comparative example of the optical terminal unit shown in FIG. 5B, the broken line B has an optical signal input level of −2 (dBm) to the optical terminal unit 2 and the RF conversion unit 23 has no optical signal. The frequency characteristic of CSO in the state where an electric current is unpowered is shown.

  In the optical terminal unit 2 according to the embodiment of the present invention shown in FIG. 4 (A), the broken line C indicates that the input level of the optical signal to the optical terminal unit 2 is −5 (dBm) and the RF conversion unit 23 Fig. 5 shows the frequency characteristics of CSO in a state where photocurrent is supplied from the power generation unit 22.

  In the second comparative example of the optical terminal unit shown in FIG. 5B, the polygonal line D indicates that the input level of the optical signal to the optical terminal unit 2 is −5 (dBm) and the RF conversion unit 23 has no optical signal. The frequency characteristic of CSO in the state where an electric current is unpowered is shown. The state in which the photocurrent is supplied from the power generation unit 22 to the RF conversion unit 23 corresponds to the reverse bias state of the photodiode, and the state in which the photocurrent is not supplied to the RF conversion unit 23 is the state of the photodiode. Corresponds to an unbiased state.

  As indicated by the broken lines A to D, when the optical input level is both −2 (dBm) and −5 (dBm), the CSO distortion performance at the time of feeding the photodiode is 10 dB from the distortion performance at the time of no feeding. This is improved. In the first comparative example of FIG. 5A, the frequency characteristics of CSO when the input level is −2 (dBm) and −5 (dBm) are substantially the same as the broken lines A and C of FIG. . That is, since the optical terminal unit 2 according to the embodiment of the present invention has substantially the same CSO characteristic as that of the first comparative example, the optical terminal unit 2 according to the embodiment of the present invention has a broadband RF signal. It is not necessary to provide a separate power supply because it does not require external power supply.

  When a non-powered photodiode is used to receive an optical signal at the optical terminal unit, due to its distortion performance, compared to the case where a fed photodiode is used at the optical terminal unit, the subscriber premises side There is a possibility that the type of signal that can be received and the band of the RF signal are limited. When the optical terminal unit composed of the non-powered photodiode of FIG. 5B is used in the system of FIGS. 1 and 8, it is not easy to obtain high distortion performance.

  Therefore, at the subscriber's home, if the FM modulation system can be operated with a level difference from the distorted signal being relatively small, even if the FM notification broadcast can be received by the FM notification broadcast terminal, it will be more effective than the FM modulation system. In a digital receiver that requires high required distortion performance, it may be difficult to view various digital broadcasts.

  On the other hand, according to the embodiment of the present invention, by using an optical terminal unit configured to supply power (photocurrent) to the other photodiode by one fed photodiode, the distortion performance is improved. Can solve the above-mentioned problems.

  Furthermore, according to the embodiment of the present invention, it is not necessary to supply power to the optical terminal unit from the outside, so that the configuration of the optical terminal unit can be simplified. Thereby, an optical terminal unit can be reduced in size. Furthermore, according to the embodiment of the present invention, it is possible to save power in the optical terminal unit. Furthermore, according to the embodiment of the present invention, it is not necessary to install a power supply for the optical terminal unit.

  FIG. 7 is a diagram showing an example of the appearance of the optical terminal unit 2 according to the embodiment of the present invention. Referring to FIG. 7, connector 20 of optical terminal unit 2 is configured to be connectable to, for example, an SC / SPC type connector. On the other hand, the connector 24 is configured to be connectable to, for example, a connector (for example, F-type plug) provided on a coaxial cable.

  According to the embodiment of the present invention, since the optical terminal unit can be reduced in size, the degree of freedom in installing the optical terminal unit can be increased. For example, the optical terminal unit 2 which concerns on embodiment of this invention can be installed in the outlet box as a part of optical outlet unit attached to the wall surface of a house. Moreover, you may set an optical terminal unit in the exterior (for example, outer wall of a house) of a house. It can also be directly connected to a terminal device in the house.

  The optical terminal unit according to the embodiment of the present invention is configured to convert one of two optical signals generated from one original optical signal into electric power and the other into an electric signal. Just do it. In the configuration shown in FIGS. 2 and 3, the optical branching device 21 is employed as the signal generation unit. The optical splitter 21 divides one optical signal into two. However, as shown in FIG. 8, the optical terminal unit 2 may include an optical demultiplexer 41 instead of the optical branching device 21.

Optical signal S ₀ is a signal in which a plurality of signals having different wavelengths are multiplexed together. Specifically, the optical signal S ₀ is the optical signal S ₂ of the optical signals S ₁ and wavelength lambda ₂ wavelength lambda ₁ is a multiplexed signal. Optical demultiplexer 41 based on the difference in wavelength, to separate the optical signals S ₁ and the optical signal S _2. By the above method, the optical demultiplexer 41 as the signal generation unit generates the optical signals S ₁ and S ₂ from the optical signal S ₀ .

  If the wavelengths are different from each other, three or more optical signals may be multiplexed. If at least one of the plurality of optical signals is converted into electric power (photocurrent) by the power generation unit 22 and at least one of the plurality of optical signals is converted into an electric signal by the RF conversion unit 23, The optical terminal unit according to the embodiment of the present invention can be applied. The number of RF conversion units is not particularly limited as long as it is 1 or more.

  In the embodiment of the present invention, the output of the optical terminal unit is divided into two systems. However, the output of the optical terminal unit may be divided into two systems and divided into two systems by a distributor during transmission.

  In the configuration shown in FIG. 1, the V-ONU and the D-ONU are accommodated in the optical terminal device 1, but the optical terminal unit 2 according to the embodiment of the present invention that is a broadcast V-ONU. It can also be applied to operation with only

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  1,101 optical terminal device, 2, optical terminal unit, 2a, 2b output (optical terminal unit), 3 FM notification broadcasting terminal, 4 digital receiver, 5 distributor, 6 TV receiver, 20 connector (optical signal reception) ), 21 optical splitter, 22 power generator, 23 RF converter, 24 connector (for electrical signal reception), 25, 26, 27 filter, 25a, 26a, 27a coil, 25b, 26b, 26c, 27c, 28 Capacitor, 27b Resistance, 31 One end (power generation unit), 32 The other end (power generation unit), 33 One end (RF conversion unit), 34 The other end (RF conversion unit), 35 Ground node, 36 Power supply node, 41 Optical demultiplexer, 51 FM broadcast transmission device, 52 Analog broadcast transmission device, 53 Terrestrial digital broadcast transmission device, 54 CATV digital broadcast transmission device, 5 BS digital broadcasting transmission apparatus, 56 110 CS digital broadcasting transmission apparatus, 57 mixer, 58 optical transmitter, 59 an optical amplifier, 60 an optical splitter, 61 an optical fiber, 62 closure.

Claims (5)

A signal generator for generating first and second optical signals from the optical signal transmitted by the optical fiber;
A first photodiode having a first anode and a grounded first cathode;
A second photodiode having a grounded second anode and a second cathode;
The first photodiode generates a photocurrent by photoelectrically converting the first optical signal, and outputs the photocurrent from the first anode.
The second photodiode converts the second optical signal into an electrical signal in a state where the photocurrent is supplied from the first anode of the first photodiode to the second cathode. An optical terminal unit that outputs the electrical signal from the second anode or the second cathode. A first filter provided between the first cathode and the ground node and blocking transmission of a high-frequency component;
A second filter provided between the first anode and the second cathode and blocking transmission of a high frequency component; and provided between the second anode and the ground node to transmit a high frequency component. A third filter for blocking
Provided between the second cathode and the second filter and between the second anode and the third filter, the second anode or the second filter; The optical terminal unit according to claim 1, further comprising an output terminal for outputting the electrical signal output from the cathode to the outside of the optical terminal unit. The signal generator is
The optical terminal unit according to claim 1, further comprising an optical branching unit that branches an input optical signal into the first and second optical signals. The optical signal input to the signal generation unit is a signal obtained by multiplexing a plurality of optical signals having different wavelengths.
The signal generator is
3. The optical terminal unit according to claim 1, further comprising: an optical demultiplexer that generates the first and second optical signals by separating the input optical signal according to a difference in wavelength. A signal transmission device for transmitting an optical broadcast signal;
An optical fiber for transmitting the optical broadcast signal sent from the signal sending device;
The optical terminal unit according to claim 1, wherein the optical broadcast signal is supplied via the optical fiber;
An optical transmission system comprising: a terminal device that receives the electrical signal output from the optical terminal unit.

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