WO2022219776A1

WO2022219776A1 - Optical power monitoring circuit, optical module, station-side device, and optical power monitoring method

Info

Publication number: WO2022219776A1
Application number: PCT/JP2021/015565
Authority: WO
Inventors: 啓祐江草; 英哲井川; 聡吉間
Original assignee: 三菱電機株式会社
Priority date: 2021-04-15
Filing date: 2021-04-15
Publication date: 2022-10-20

Abstract

The present invention comprises: an optical receiver (120-1) that receives a first optical signal having a first rate and outputs a first monitor current proportional to an electric current converted according to the optical power of the first optical signal; a receiver (120-2) that receives a second optical signal having a second rate different from the first rate and outputs a second monitor current proportional to an electric current converted according to the optical power of the second optical signal; a route switcher (130) that receives inputs of the first monitor current and the second monitor current and switches an output monitor current to be output between the first monitor current and the second monitor current; and an MCU (140) that generates a monitor signal for monitoring the optical power of the first optical signal or the optical power of the second optical signal depending on the output monitor current.

Description

Optical power monitor circuit, optical module, office equipment, and optical power monitor method

The present disclosure relates to an optical power monitoring circuit, an optical module, a station-side device, and an optical power monitoring method.

2. Description of the Related Art An access network for providing multimedia services to each home widely uses an optical communication system called a PON (Passive Optical Network) system implemented by a public network using optical fibers.
A PON system consists of one OLT (Optical Line Terminal), which is an optical subscriber line terminal used as a station-side device, and a plurality of subscriber-side terminal devices connected via an optical star coupler. It is composed of ONUs (Optical Network Units), which are optical network devices.

In the PON system, the OLT sends continuous signals to all ONUs.
On the other hand, an optical packet signal transmitted from each ONU is time-division multiplexed and received by the OLT. For this reason, an optical receiver provided in an OLT generally requires a burst reception function for instantaneously electrically regenerating an optical packet signal.

Optical transceivers used in OLT are widely used optical modules having functions and external shapes defined by specifications such as XFP (10 Gigabit Small Form Factor Pluggable) or SFP+ (Small Form Factor Pluggable Plus). An XFP or SFP+ optical module is required to output a monitor signal for monitoring the optical intensity of a received packet. For example, a monitor signal is output several hundred ns after an RSSI (Received Signal Strength Indication) trigger signal is input from a MAC-IC (Media Access Control-Integrated Circuit).

A power monitor circuit that satisfies such requirements generally comprises a current mirror circuit and a sample-and-hold circuit, as disclosed in US Pat.
In such a power monitor circuit, an APD current, which is a current proportional to the intensity of an optical signal input to an APD (Avalanche Photo Diode), which is a light receiving element, is input to a current mirror circuit. The current mirror circuit generates a mirror current proportional to the APD current, the mirror current is converted into a voltage in the subsequent circuit, and the converted voltage is output. A sample-and-hold circuit holds the voltage value of the converted voltage. The voltage value held by the sample-and-hold circuit is converted into a digital value by AD (Analog to Digital) conversion. Using this digital value, it becomes possible to monitor the power of the received light.

JP 2015-103914

In recent years, multi-rate compatible systems such as MPM-PON (Multi Point Module PON) capable of receiving received signals of multiple rates are becoming widespread.
In order to achieve multi-rate reception of received signals of a plurality of rates with the conventional configuration, a circuit for receiving received light for each rate and monitoring the power of the received light is required. Therefore, there is a problem that the size of the optical receiver increases. Moreover, there is also the problem that power consumption increases due to the plurality of circuits, and the cost of the device increases due to the increase in the number of parts.

An object of one or more aspects of the present disclosure is to integrate part of a circuit that receives received light and monitors the power of the received light.

An optical power monitoring circuit according to one aspect of the present disclosure receives a first optical signal that is an optical signal at a first rate, and converts a current according to the optical power of the first optical signal into A first optical receiver that outputs a first monitor current that is a proportional current; a second optical receiver that outputs a second monitor current that is proportional to the current converted according to the optical power of the two optical signals; a path switching unit that receives an input and switches an output monitor current, which is a monitor current to be output, between the first monitor current and the second monitor current; and a control unit that generates a monitor signal for monitoring the optical power of the optical signal or the optical power of the second optical signal.

An optical power monitoring method according to one aspect of the present disclosure receives a first optical signal, which is an optical signal at a first rate, and converts a current proportional to the optical power of the first optical signal. receiving a second optical signal that is an optical signal at a second rate different from the first rate, and adjusting the optical power of the second optical signal to outputs a second monitor current that is a current proportional to the current converted according to , for switching between the first monitor current and the second monitor current and monitoring the optical power of the first optical signal or the optical power of the second optical signal in response to the output monitor current. is characterized by generating a monitor signal of

According to one or more aspects of the present disclosure, part of the circuit that receives received light and monitors the power of the received light can be consolidated.

1 is a block diagram schematically showing the configuration of an optical communication system including an OLT according to Embodiments 1-5; FIG. 2 is a block diagram schematically showing the configuration of an optical receiver included in the OLT according to Embodiment 1; FIG. FIG. 4 is a block diagram schematically showing the configuration of an optical receiver included in an OLT according to Embodiment 2; FIG. 9 is a block diagram schematically showing the configuration of an optical receiver that is a modification of Embodiment 2; FIG. 11 is a block diagram schematically showing the configuration of an optical receiver included in an OLT according to Embodiment 3; FIG. 12 is a block diagram schematically showing the configuration of an optical receiver that is a modification of Embodiment 3; 14 is a block diagram schematically showing the configuration of an optical receiver included in an OLT according to Embodiment 4; FIG. FIG. 12 is a block diagram schematically showing the configuration of an optical receiver that is a modification of Embodiment 4; 14 is a block diagram schematically showing the configuration of an optical receiver included in an OLT according to Embodiment 5; FIG. FIG. 14 is a block diagram schematically showing the configuration of an optical receiver that is a modification of Embodiment 5;

Embodiment 1.
FIG. 1 is a block diagram schematically showing the configuration of an optical communication system 100 including an OLT 110 according to Embodiment 1. As shown in FIG.
The optical communication system 100 is a PON system in the form of point-to-multipoint.

The optical communication system 100 includes one OLT 110 as a station-side device, a plurality of ONUs 101, and an optical star coupler 102 that passively branches or joins optical signals. All ONUs 101 are connected to OLT 110 via one or more optical star couplers 102 and optical fibers 103 .

The OLT 110 comprises a wavelength multiplexing coupler 112 , an optical transmitter 113 , an optical receiver 114 and a signal processor 115 . As shown in FIG. 1, one optical module 111 may be configured to include at least a wavelength multiplexing coupler 112, an optical transmitter 113 and an optical receiver 114. FIG.

The wavelength multiplexing coupler 112 outputs upstream and downstream signals with different optical wavelengths in predetermined directions. The wavelength multiplexing coupler 112 outputs the optical signal output from the ONU 101 and transmitted through the optical fiber 103 to the optical receiver 114 side, and transmits the optical signal output from the optical transmitter 113 to the ONU 101. Output to the optical fiber 103 side.

The optical transmitter 113 modulates light emitted by a light emitting element such as a semiconductor laser with a transmission signal input from the signal processing section 115 . An optical signal generated by modulation is output as a downstream signal via the wavelength multiplexing coupler 112 , transmitted through the optical fiber 103 , and received by each ONU 101 .

An upstream signal, which is an optical signal transmitted from the ONU 101 and transmitted through the optical fiber 103 , is input to the optical receiver 114 via the wavelength multiplexing coupler 112 . The optical receiver 114 photoelectrically converts the input optical signal, demodulates it into a received voltage signal in a subsequent circuit, and outputs it to the signal processing unit 115 .

The signal processing unit 115 includes a MAC-IC that processes transmitted and received signals. The MAC-IC of the signal processing unit 115 generates a transmission signal based on the baseband signal input from the network 104 such as the Internet, and outputs the transmission signal to the optical transmitter 113 . The signal processing unit 115 also converts the received signal input from the optical receiver 114 into a baseband signal and outputs the baseband signal to the network 104 .

FIG. 2 is a block diagram schematically showing the configuration of optical receiver 114 included in OLT 110 according to the first embodiment.
The optical receiver 114 functions as an optical power monitor circuit.
Embodiment 1 describes the case of receiving a continuous signal as the most basic configuration.

The optical receiver 114 in Embodiment 1 includes an optical receiver 120-1 as a first optical receiver, an optical receiver 120-2 as a second optical receiver, a path switching unit 130, and an MCU (Micro Controller Unit) 140.

The optical receiver 120-1 is a first optical receiver circuit that receives a first optical signal that is an optical signal at a certain rate. The rate of the first optical signal is also called the first rate. The optical receiver 120-1 outputs a first monitor current that is proportional to the current converted according to the optical power of the first optical signal.

The optical receiver 120-1 includes a light receiving element 121-1, a current mirror circuit 122-1, a power supply 123-1, and a power supply voltage controller 124-1.

The light receiving element 121-1 converts the received first optical signal into a current signal. The light receiving element 121-1 gives the converted current signal as a first input current to the current mirror circuit 122-1.
The current mirror circuit 122-1 outputs to the path switching section 130 a first monitor current proportional to the first input current from the light receiving element 121-1.
A power supply 123-1 is a power supply for the light receiving element 121-1.
The power supply voltage control section 124-1 controls the power supply voltage of the power supply 123-1.

Also, the optical receiver 120-2 is a second optical receiver circuit that receives a second optical signal that is an optical signal with a rate different from that of the first optical signal. The rate of the second optical signal is also called the second rate. The optical receiver 120-2 outputs a second monitor current that is proportional to the current converted according to the optical power of the second optical signal.

The optical receiver 120-2 includes a light receiving element 121-2, a current mirror circuit 122-2, a power supply 123-2, and a power supply voltage controller 124-2.

The light receiving element 121-2 converts the received second optical signal into a current signal. The light receiving element 121-2 gives the converted current signal to the current mirror circuit 122-2 as a second input current.
The current mirror circuit 122-2 outputs to the path switching section 130 a second monitor current proportional to the second input current from the light receiving element 121-2.
A power supply 123-2 is a power supply for the light receiving element 121-2.
The power supply voltage control section 124-2 controls the power supply voltage of the power supply 123-2.

Path switching section 130 receives the input of the first monitor current from optical receiving section 120-1, receives the input of the second monitoring current from optical receiving section 120-2, and outputs monitor current, which is output monitor current. between the first monitor current and the second monitor current.
For example, the path switching unit 130 is a path switching circuit that switches the monitor current output to the MCU 140 between the first monitor current and the second monitor current according to the path switching signal indicating the instruction from the signal processing unit 115. . Specifically, when monitoring of the first optical signal is selected by the path switching signal, the path switching unit 130 connects the current mirror circuit 122-1 and the MCU 140 to monitor the second optical signal. When selected, the current mirror circuit 122-2 and the MCU 140 are connected.

MCU 140 generates a monitor signal for monitoring the optical power of the first optical signal or the optical power of the second optical signal according to the output monitor current from path switching section 130 .
The MCU 140 converts the output of the current mirror circuit 122-1 or current mirror circuit 122-2 into a digital signal using an ADC (Analog to Digital Converter) 141, and generates a monitor signal based on the converted digital signal. The output of the current mirror circuit 122-1 or current mirror circuit 122-2 is a current, and the MCU 140 generates a monitor signal by obtaining a digital-converted voltage value corresponding to the current. The monitor signal is output to signal processing section 115 .
For example, the MCU 140 includes a processor such as a CPU (Central Processing Unit) and memory.

Returning to FIG. 1 , the signal processor 115 outputs a path switching signal to the optical receiver 114 . For example, the signal processing unit 115 outputs a path switching signal to the path switching unit 130 when switching between monitoring the first optical signal and monitoring the second optical signal. It need not be output by the processing unit 115 .
Also, the signal processing unit 115 receives a monitor signal from the MCU 140 and performs known processing.

As described above, according to Embodiment 1, it is possible to switch the optical signal to be monitored as needed, so that the path switching unit 130 and subsequent components of the optical receiver 114 can be integrated. Therefore, it is possible to realize miniaturization, low power consumption, and low cost of the OLT 110 .

Embodiment 2.
Embodiment 2 describes a case of performing burst reception.
As shown in FIG. 1, an optical communication system 200 including an OLT 210 according to Embodiment 2 includes one OLT 210 as a station-side device, a plurality of ONUs 201, and passively branch or join optical signals. and an optical star coupler 102 that All ONUs 201 are connected to OLT 210 via one or more optical star couplers 102 and optical fibers 103 .

In the second embodiment, the optical signal transmitted from each ONU 201 is a burst optical packet signal, and the optical signal obtained by time-division multiplexing them is input to the OLT 210 .

The OLT 210 includes an optical module 211 and a signal processing section 215 .
The optical module 211 transmits and receives optical signals. The optical module 211 includes a wavelength multiplexing coupler 112 , an optical transmitter 113 and an optical receiver 214 .
The wavelength multiplexing coupler 112 and the optical transmitter 113 of the optical module 211 according to the second embodiment are the same as the wavelength multiplexing coupler 112 and the optical transmitter 113 of the optical module 111 according to the first embodiment.

As described above, in the second embodiment, the ONU 201 transmits burst optical packet signals as optical signals. Since each ONU 201 is connected to the OLT 210 via an arbitrary length of optical fiber 103 and an arbitrary number of optical star couplers 102, the intensity of the optical signal received by the optical receiver 214 of the OLT 210 is equal to the optical packet It varies greatly from signal to signal. Therefore, in order for the optical receiver 214 to stably receive the optical packet signal, it is necessary to have a power monitor function capable of quickly acquiring the optical input power of the optical signal with a wide dynamic range.

FIG. 3 is a block diagram schematically showing the configuration of optical receiver 214 included in OLT 210 according to the second embodiment.
Optical receiver 214 in the second embodiment includes optical receiver 120 - 1 , optical receiver 120 - 2 , path switching section 230 , MCU 240 , and S/H (Sample and Hold) circuit 250 .
Optical receiver 120-1 and optical receiver 120-2 of optical receiver 214 in the second embodiment are the same as optical receiver 120-1 and optical receiver 120-2 of optical receiver 114 in the first embodiment. is.

The path switching section 230 switches the monitor current output to the S/H circuit 250 between the first monitor current and the second monitor current according to the monitor request signal indicating the instruction from the signal processing section 215 . For example, the path switching unit 230 connects the current mirror circuit 122-1 and the S/H circuit 250 when receiving the first monitor request signal, and connects the current mirror circuit 122-1 and the S/H circuit 250 when receiving the second monitor request signal. connects the current mirror circuit 122 - 2 and the S/H circuit 250 .

Here, the first monitor request signal is a signal requesting monitoring of the optical power of the first optical signal, and the second monitor request signal is a signal requesting monitoring of the optical power of the second optical signal. is.
Therefore, the path switching section 230 outputs the first monitor current as the output monitor current in response to the first monitor request signal, and outputs the second monitor current as the output monitor current in response to the second monitor request signal. output as
If the path switching unit 230 has already connected the current mirror circuit 122-1 and the S/H circuit 250 when the first monitor request signal is input, the state is maintained. Further, even if the path switching unit 230 has already connected the current mirror circuit 122-2 and the S/H circuit 250 when the second monitor request signal is input, the state is similarly maintained. .

Here, the response speed of the path switching unit 230 must satisfy system requirements. For example, considering the reception of burst signals, it is conceivable to use a switch IC or the like capable of responding in the order of several nanoseconds to several tens of nanoseconds as the path switching unit 230 .

The S/H circuit 250 is a sample-and-hold section that receives the input of the output monitor current from the path switching section 230, samples the monitor voltage corresponding to the output monitor current, and holds it.
In the second embodiment, after the first monitor request signal or the second monitor request signal is input to the S/H circuit 250, a sufficient time has passed for the path switching unit 230 to switch paths. Later, the monitor voltage corresponding to the output of the current mirror circuit 122-1 or current mirror circuit 122-2 is sampled and held. Here, the monitor voltage from the current mirror circuit 122-1 is also called the first monitor voltage, and the monitor voltage from the current mirror circuit 122-2 is also called the second monitor voltage.

Therefore, the S/H circuit 250 samples and holds the monitor voltage corresponding to the first monitor current in response to the first monitor request signal, and responds to the second monitor request signal to respond to the second monitor request signal. sample and hold the monitor voltage corresponding to the monitor current of .
When the first monitor request signal and the second monitor request signal are input at the same time, it is possible to respond by sequential processing by determining in advance in the system which one should be prioritized.

The MCU 240 converts the output from the S/H circuit 250 into a digital signal with the ADC 141 and generates a monitor signal based on the converted digital signal. For example, the MCU 240 generates a monitor signal by digitally converting the monitor voltage.

Returning to FIG. 1, the signal processing unit 215 includes a MAC-IC that processes transmission/reception signals. The MAC-IC of the signal processing unit 215 generates a transmission signal based on the baseband signal input from the network 104 such as the Internet, and outputs the transmission signal to the optical transmitter 113 . The signal processing unit 215 also converts the received signal input from the optical receiver 214 into a baseband signal and outputs the baseband signal to the network 104 .
In Embodiment 2, the signal processor 215 outputs the first monitor request signal or the second monitor request signal to the optical receiver 214 . For example, when the signal processing unit 215 selects monitoring of the first optical signal, the signal processing unit 215 outputs the first monitor request signal to the path switching unit 230 and the S/H circuit 250, and monitors the second optical signal. is selected, a second monitor request signal is output to the path switching unit 230 and the S/H circuit 250 . Note that the monitor request signal does not necessarily have to be output by the signal processing unit 215 .
Also, the signal processing unit 215 receives a monitor signal from the MCU 240 and performs known processing.

As described above, even in the second embodiment, since the optical signal to be monitored is configured to be switched as necessary, it is possible to integrate the path switching unit 230 and the subsequent parts of the optical receiver 214. . This makes it possible to reduce the size, power consumption, and cost of the OLT 210 .

In Embodiment 2 described above, two optical receivers 120-1 and 120-2 are provided, and two rates are supported, but this number is not limited to two. . For example, like the optical receiver 214# shown in FIG. 4, optical receivers 120-1, 120-2, . ), an arbitrary number of three or more rates can be supported.
In such a case, the signal processing section 215 outputs the first monitor request signal, the second monitor request signal, .

By adopting such a configuration based on Embodiment 2, as long as the response speed of the path switching section 230 satisfies the system requirements, it is possible to monitor any number of received signals with different rates.

Embodiment 3.
Embodiment 3 also describes the case of performing burst reception.
As shown in FIG. 1, an optical communication system 300 including an OLT 310 according to Embodiment 3 includes one OLT 310 as a station-side device, a plurality of ONUs 201, and passively branch or join optical signals. and an optical star coupler 102 that All ONUs 201 are connected to OLT 210 via one or more optical star couplers 102 and optical fibers 103 .

ONU 201 in optical communication system 300 in the third embodiment is configured in the same manner as ONU 201 in optical communication system 200 in the second embodiment.
Therefore, the optical signal transmitted from each ONU 201 is a burst optical packet signal, and the optical signal obtained by time-division multiplexing them is input to the OLT 310 .

The OLT 310 includes an optical module 311 and a signal processing section 315 .
The optical module 311 transmits and receives optical signals. The optical module 311 includes a wavelength multiplexing coupler 112 , an optical transmitter 113 and an optical receiver 314 .
The wavelength multiplexing coupler 112 and the optical transmitter 113 of the optical module 311 according to the third embodiment are the same as the wavelength multiplexing coupler 112 and the optical transmitter 113 of the optical module 111 according to the first embodiment.

FIG. 5 is a block diagram schematically showing the configuration of optical receiver 314 included in OLT 310 according to the third embodiment.
Optical receiver 314 in Embodiment 3 includes optical receiver 120-1, optical receiver 120-2, path switching unit 330, MCU 240, and S/H circuit 250. FIG.
Optical receiver 120-1 and optical receiver 120-2 of optical receiver 314 in Embodiment 3 are the same as optical receiver 120-1 and optical receiver 120-2 of optical receiver 114 in Embodiment 1. is.
Also, the S/H circuit 250 and the MCU 240 of the optical receiver 314 in the third embodiment are the same as the S/H circuit 250 and the MCU 240 in the second embodiment.

The path switching section 330 switches the monitor current output to the S/H circuit 350 between the first monitor current and the second monitor current according to the monitor request signal indicating the instruction from the signal processing section 315 . For example, path switching section 330 normally connects current mirror circuit 122 - 1 and S/H circuit 350 . Then, upon receiving the second monitor request signal, the path switching unit 330 connects the current mirror circuit 122-2 and the S/H circuit 250, and after a predetermined period elapses, the current mirror circuit 122 - 1 and the S/H circuit 250 .
Therefore, the path switching unit 330 outputs the second monitor current as the output monitor current in response to the second monitor request signal, and outputs the first monitor current after a certain period of time has passed since receiving the second monitor request signal. Output current as output monitor current.

Path switching section 330 normally connects current mirror circuit 122-2 and S/H circuit 250, and path switching section 330 switches current mirror circuit 122-2 when receiving the second monitor request signal. -1 and the S/H circuit 250 may be connected, and the connection between the current mirror circuit 122-2 and the S/H circuit 250 may be restored after a predetermined period of time has elapsed.
In this case, the path switching unit 330 outputs the first monitor current as the output monitor current in response to the first monitor request signal, and outputs the second monitor current after a certain period of time has passed since receiving the first monitor request signal. Output the monitor current as the output monitor current.

Returning to FIG. 1, the signal processing unit 315 includes a MAC-IC that processes transmission/reception signals. The MAC-IC of the signal processing unit 315 generates a transmission signal based on the baseband signal input from the network 104 such as the Internet, and outputs the transmission signal to the optical transmitter 113 . The signal processing unit 315 also converts the received signal input from the optical receiver 314 into a baseband signal and outputs the baseband signal to the network 104 .
Also in Embodiment 3, the signal processing unit 315 outputs the first monitor request signal or the second monitor request signal to the optical receiver 314, as will be described later. For example, the signal processing unit 315 outputs the first monitor request signal to the S/H circuit 250 when selecting the monitoring of the first optical signal, and outputs the first monitoring request signal when selecting the monitoring of the second optical signal. outputs a second monitor request signal to the path switching unit 330 and the S/H circuit 250 . Note that the monitor request signal does not necessarily have to be output by the signal processing section 315 .
Also, the signal processing unit 315 receives a monitor signal from the MCU 240 and performs known processing.

As described above, in the third embodiment, as compared with the second embodiment, the processing by the first monitor request signal is reduced. Effects similar to those of form 2 can be achieved.

In Embodiment 3 described above, two optical receivers 120-1 and 120-2 are provided and two rates are supported, but this number is not limited to two. . For example, like the optical receiver 314# shown in FIG. 6, optical receivers 120-1, 120-2, . ), an arbitrary number of three or more rates can be supported.
In such a case, the signal processing unit 315 outputs the first monitor request signal to the S/H circuit 250, and outputs the second monitor request signal, . Output to S/H circuit 250 .

By adopting such a configuration based on Embodiment 3, as long as the response speed of the path switching section 330 satisfies the system requirements, it is possible to monitor any number of received signals with different rates.

Embodiment 4.
Embodiment 4 also describes the case of performing burst reception.
As shown in FIG. 1, an optical communication system 400 including an OLT 410 according to Embodiment 4 includes one OLT 410 as a station-side device, a plurality of ONUs 201, and passively branch or join optical signals. and an optical star coupler 102 that All ONUs 201 are connected to OLT 210 via one or more optical star couplers 102 and optical fibers 103 .

ONU 201 in optical communication system 400 in the fourth embodiment is configured in the same manner as ONU 201 in optical communication system 200 in the second embodiment.
Therefore, the optical signal transmitted from each ONU 201 is a burst optical packet signal, and the optical signal obtained by time-division multiplexing them is input to the OLT 410 .

The OLT 410 includes an optical module 411 and a signal processing section 415 .
The optical module 411 transmits and receives optical signals. The optical module 411 includes a wavelength multiplexing coupler 112 , an optical transmitter 113 and an optical receiver 414 .
The wavelength multiplexing coupler 112 and the optical transmitter 113 of the optical module 411 in the fourth embodiment are the same as the wavelength multiplexing coupler 112 and the optical transmitter 113 of the optical module 111 in the first embodiment.

FIG. 7 is a block diagram schematically showing the configuration of optical receiver 414 included in OLT 410 according to the fourth embodiment.
Optical receiver 414 in Embodiment 4 includes optical receiver 120-1, optical receiver 120-2, path switching unit 430, MCU 440, and S/H circuit 450. FIG.
Optical receiver 120-1 and optical receiver 120-2 of optical receiver 414 in Embodiment 4 are the same as optical receiver 120-1 and optical receiver 120-2 of optical receiver 114 in Embodiment 1. is.

The path switching unit 430 switches the output monitor current, which is the monitor current to be output to the S/H circuit 450, between the first monitor current and the second monitor current at a predetermined cycle.
It should be noted that the cycle of switching the route of the route switching unit 430 must satisfy the system requirements.

When the path switching unit 430 connects the current mirror circuit 122-1 and the S/H circuit 450, the S/H circuit 450 samples and holds the monitor voltage.
The MCU 440 converts the monitor voltage held by the S/H circuit 450 into a digital signal using the ADC 141, and generates a monitor signal based on the converted digital signal. The MCU 440 stores the generated monitor signal as the monitor value of the first optical signal.

Further, when the current mirror circuit 122-2 and the S/H circuit 450 are connected by the path switching unit 430, the S/H circuit 450 samples and holds the monitor voltage.
The MCU 440 converts the monitor voltage held by the S/H circuit 450 into a digital signal using the ADC 141, and generates a monitor signal based on the converted digital signal. The MCU 440 stores the generated monitor signal as the monitor value of the second optical signal.

In other words, the MCU 440 stores the monitor value of the first optical signal and the monitor value of the second optical signal. The MCU 440 then updates these monitor values according to the cycle at which the path switching unit 430 switches paths.

When the first monitor request signal is input, the MCU 440 outputs the monitor value of the first optical signal as the monitor signal, and when the second monitor request signal is input, the MCU 440 outputs the monitor value of the second optical signal. Output the monitor value as a monitor signal.

Returning to FIG. 1, the signal processing unit 415 includes a MAC-IC that processes transmission/reception signals. The MAC-IC of the signal processing unit 415 generates a transmission signal based on the baseband signal input from the network 104 such as the Internet, and outputs the transmission signal to the optical transmitter 113 . Also, the signal processing unit 415 converts the received signal input from the optical receiver 414 into a baseband signal and outputs the baseband signal to the network 104 .
Also in Embodiment 4, the signal processing unit 415 outputs the first monitor request signal or the second monitor request signal to the optical receiver 414, as will be described later. For example, the signal processing unit 415 outputs the first monitor request signal to the MCU 440 when selecting the monitoring of the first optical signal, and outputs the first monitor request signal to the MCU 440 when selecting the monitoring of the second optical signal. Output a second monitor request signal. Note that the monitor request signal does not necessarily have to be output by the signal processing unit 415 .
Also, the signal processing unit 415 receives a monitor signal from the MCU 440 and performs known processing.

As described above, according to Embodiment 4, even when the first monitor request signal and the second monitor request signal are input at the same time, the MCU 440 can output each monitor value.

In Embodiment 4 described above, two optical receivers 120-1 and 120-2 are provided and two rates are supported, but this number is not limited to two. . For example, like the optical receiver 414# shown in FIG. 8, optical receivers 120-1, 120-2, . ), an arbitrary number of three or more rates can be supported.
In such a case, the signal processing section 415 outputs a first monitor request signal, a second monitor request signal, . . .

By adopting such a configuration based on the fourth embodiment, as long as the response speed of the path switching section 430 satisfies the system requirements, it is possible to monitor any number of received signals with different rates.

Embodiment 5.
Embodiment 5 also describes the case of performing burst reception.
As shown in FIG. 1, an optical communication system 500 including an OLT 510 according to Embodiment 5 includes one OLT 510 as a station-side device, a plurality of ONUs 201, and passively branch or join optical signals. and an optical star coupler 102 that All ONUs 201 are connected to OLT 210 via one or more optical star couplers 102 and optical fibers 103 .

ONU 201 in optical communication system 500 according to the fifth embodiment is configured similarly to ONU 201 in optical communication system 200 according to the second embodiment.
Therefore, the optical signal transmitted from each ONU 201 is a burst optical packet signal, and the optical signal obtained by time-division multiplexing them is input to the OLT 510 .

The OLT 510 includes an optical module 511 and a signal processing section 515 .
The optical module 511 transmits and receives optical signals. The optical module 511 includes a wavelength multiplexing coupler 112 , an optical transmitter 113 and an optical receiver 514 .
The wavelength multiplexing coupler 112 and the optical transmitter 113 of the optical module 511 according to the fifth embodiment are the same as the wavelength multiplexing coupler 112 and the optical transmitter 113 of the optical module 111 according to the first embodiment.

FIG. 9 is a block diagram schematically showing the configuration of optical receiver 514 included in OLT 510 according to the fifth embodiment.
Optical receiver 514 in Embodiment 5 includes optical receiver 120-1, optical receiver 120-2, path switching unit 530, MCU 540, and S/H circuit 550. FIG.
Optical receiver 120-1 and optical receiver 120-2 of optical receiver 514 in Embodiment 5 are the same as optical receiver 120-1 and optical receiver 120-2 of optical receiver 114 in Embodiment 1. is.

When the first monitor request signal is input, the MCU 540 provides the path switching section 530 and the S/H circuit 550 with a first control signal, which is a control signal instructing monitoring of the first optical signal.

Path switching section 530 that has received the first control signal connects current mirror circuit 122 - 1 and S/H circuit 550 .
Upon receiving the first control signal, the S/H circuit 550 samples the monitor voltage corresponding to the output of the current mirror circuit 122-1 after a time sufficient for the path switching section 530 to switch paths. and hold.
MCU 540 generates a monitor signal based on the output voltage of S/H circuit 550 .

Also, when the second monitor request signal is input, the MCU 540 provides the path switching section 530 and the S/H circuit 550 with a second control signal, which is a control signal instructing monitoring of the second optical signal.

Upon receiving the second control signal, the path switching section 530 connects the current mirror circuit 122-2 and the S/H circuit 550 to each other.
Upon receiving the second control signal, the S/H circuit 550 samples the monitor voltage corresponding to the output of the current mirror circuit 122-2 after a time sufficient for the path switching unit 530 to switch paths. and hold.
MCU 540 generates a monitor signal based on the output voltage of S/H circuit 550 .

In other words, the MCU 540 outputs the first control signal to the path switching unit 530 and the S/H circuit 550 in response to the first monitor request signal, and outputs the second control signal in response to the second monitor request signal. A signal is output to the path switching section 530 and the S/H circuit 550 .
Then, the path switching section 530 outputs the first monitor current as the output monitor current in response to the first control signal, and outputs the second monitor current as the output monitor current in response to the second control signal. do.
Furthermore, the S/H circuit 550 samples and holds the monitor voltage corresponding to the first monitor current in response to the first control signal, and the second monitor current in response to the second control signal. The monitor voltage corresponding to is sampled and held.

Note that when the first monitor request signal and the second monitor request signal are input to the MCU 540 at the same time, the system can determine in advance which one to prioritize, so that sequential processing can be performed.

Returning to FIG. 1, the signal processing unit 515 includes a MAC-IC that processes transmission/reception signals. The MAC-IC of the signal processing unit 515 generates a transmission signal based on the baseband signal input from the network 104 such as the Internet, and outputs the transmission signal to the optical transmitter 113 . Also, the signal processing unit 515 converts the received signal input from the optical receiver 514 into a baseband signal and outputs the baseband signal to the network 104 .
Also in Embodiment 5, the signal processing unit 515 outputs the first monitor request signal or the second monitor request signal to the optical receiver 514, as will be described later. For example, the signal processing unit 515 outputs a first monitor request signal to the MCU 540 when selecting monitoring of the first optical signal, and outputs a signal to the MCU 540 when selecting monitoring of the second optical signal. Output a second monitor request signal. Note that the monitor request signal does not necessarily have to be output by the signal processing section 515 .
Also, the signal processing unit 515 receives a monitor signal from the MCU 540 and performs known processing.

As described above, according to the fifth embodiment, a plurality of monitor requests such as monitoring the first optical signal at 0 level and monitoring the second optical signal at 1 level can be combined into a single request. It can correspond to the system input by the signal line.

In the fifth embodiment described above, two optical receivers 120-1 and 120-2 are provided and correspond to two rates, but this number is not limited to two. . For example, like optical receiver 514# shown in FIG. 10, optical receiver 120-1, optical receiver 120-2, . ), an arbitrary number of three or more rates can be supported.
In such a case, the signal processing unit 515 outputs a first monitor request signal, a second monitor request signal, . . .

By adopting such a configuration based on Embodiment 5, as long as the response speed of the path switching section 530 satisfies the system requirements, it is possible to monitor any number of received signals with different rates.

100, 200, 300, 400, 500 optical communication system, 101, 201 ONU, 102 optical star coupler, 103 optical fiber, 110, 210, 310, 410, 510 OLT, 111, 211, 311, 411, 511 optical module, 112 Wavelength multiplex coupler, 113 optical transmitter, 114, 214, 314, 414, 514 optical receiver, 115, 215, 315, 415, 515 signal processor, 120-1 optical receiver, 121-1 light receiving element, 122 -1 Current mirror circuit, 123-1 Power supply, 124-1 Power supply voltage control unit, 120-2 Optical receiver unit, 121-2 Light receiving element, 122-2 Current mirror circuit, 123-2 Power supply, 124-2 Power supply voltage control section, 130, 230, 330, 430, 530 path switching section, 140, 240, 440, 540 MCU, 141 ADC, 250, 450, 550 S/H circuit.

Claims

receiving a first optical signal, which is an optical signal at a first rate, and outputting a first monitor current, which is a current proportional to the current converted according to the optical power of the first optical signal; one optical receiver;
receiving a second optical signal that is an optical signal at a second rate different from the first rate, and receiving a second optical signal that is proportional to the current converted according to the optical power of the second optical signal; a second optical receiver that outputs two monitor currents;
A path switching unit that receives inputs of the first monitor current and the second monitor current and switches an output monitor current, which is a monitor current to be output, between the first monitor current and the second monitor current. When,
and a control unit that generates a monitor signal for monitoring the optical power of the first optical signal or the optical power of the second optical signal according to the output monitor current. Circuit for monitoring.
a sample-and-hold unit that receives an input of the output monitor current, samples a monitor voltage corresponding to the output monitor current, and holds the monitor voltage;
2. The optical power monitor circuit according to claim 1, wherein the control unit generates the monitor signal by digitally converting the monitor voltage.
The path switching unit outputs the first monitor current as the output monitor current in response to a first monitor request signal requesting monitoring of the optical power of the first optical signal, outputting the second monitor current as the output monitor current in response to a second monitor request signal requesting monitoring of the optical power of the signal;
The sample-and-hold section samples and holds the monitor voltage corresponding to the first monitor current in response to the first monitor request signal, and the 3. The optical power monitor circuit according to claim 2, wherein said monitor voltage corresponding to a second monitor current is sampled and held.
The path switching unit outputs the first monitor current as the output monitor current in response to a first monitor request signal requesting monitoring of the optical power of the first optical signal, and outputs the first monitor current as the output monitor current. outputting the second monitor current as the output monitor current after a certain period of time has elapsed since receiving the request signal;
The sample-and-hold unit samples and holds the monitor voltage corresponding to the first monitor current in response to the first monitor request signal, and monitors the optical power of the second optical signal. 3. The optical power monitor circuit according to claim 2, wherein said monitor voltage corresponding to said second monitor current is sampled and held in response to a requesting second monitor request signal.
The path switching unit switches the output monitor current between the first monitor current and the second monitor current at a predetermined cycle,
The sample-and-hold unit samples and holds the monitor voltage corresponding to the first monitor current according to the cycle, and performs a second request for monitoring the optical power of the second optical signal. sampling and holding the monitor voltage corresponding to the second monitor current in response to a monitor request signal;
The control unit acquires the monitor voltage corresponding to the first monitor current from the sample and hold unit, generates the monitor signal, and outputs the second monitor current from the sample and hold unit. obtaining the corresponding monitor voltage to generate the monitor signal; and corresponding to the first monitor current in response to a first monitor request signal requesting monitoring of the optical power of the first optical signal. outputting the monitor signal generated from the monitor voltage, and outputting the monitor signal generated from the monitor voltage corresponding to the second monitor current in response to the second monitor request signal. 3. The optical power monitor circuit according to claim 2.
The control section outputs a first control signal to the path switching section and the sample and hold section in response to a first monitor request signal requesting monitoring of the optical power of the first optical signal, outputting a second control signal to the path switching unit and the sample and hold unit in response to a second monitor request signal requesting monitoring of the optical power of the two optical signals;
The path switching unit outputs the first monitor current as the output monitor current according to the first control signal, and outputs the second monitor current according to the second control signal. Output as monitor current,
The sample-and-hold section samples and holds the monitor voltage corresponding to the first monitor current in response to the first control signal, and samples and holds the second monitor voltage in response to the second control signal. 3. The optical power monitor circuit according to claim 2, wherein said monitor voltage corresponding to the monitor current of is sampled and held.
An optical module comprising the optical power monitor circuit according to claim 1 .
A station-side apparatus comprising the optical power monitor circuit according to any one of claims 1 to 6.
receiving a first optical signal, which is an optical signal at a first rate, and outputting a first monitor current, which is a current proportional to the current converted according to the optical power of the first optical signal;
receiving a second optical signal that is an optical signal at a second rate different from the first rate, and receiving a second optical signal that is proportional to the current converted according to the optical power of the second optical signal; outputs two monitor currents,
receiving inputs of the first monitor current and the second monitor current and switching an output monitor current, which is a monitor current to be output, between the first monitor current and the second monitor current;
An optical power monitoring method, comprising generating a monitor signal for monitoring the optical power of the first optical signal or the optical power of the second optical signal according to the output monitor current.