WO2016077952A1

WO2016077952A1 - Optical line terminal, optical network unit, and passive optical network system

Info

Publication number: WO2016077952A1
Application number: PCT/CN2014/091254
Authority: WO
Inventors: 刘德坤; 高建河
Original assignee: 华为技术有限公司
Priority date: 2014-11-17
Filing date: 2014-11-17
Publication date: 2016-05-26
Also published as: CN106165327A; CN106165327B

Abstract

Disclosed is a time and wavelength division multiplexing-passive optical network (TWDM-PON) system. The system comprises an optical line terminal (OLT), an optical distribution network (ODN), and at least one optical network unit (ONU) or optical network terminal (ONT). The OLT comprises a wavelength tunable demultiplexer that has one common port and four branch ports. The OLT is used for controlling the wavelength tunable demultiplexer so that all optical signals transmitted from the ONU or the ONT and entering from the common port of the wavelength tunable demultiplexer are demultiplexed into a first port of the four branch ports and enter a first receiver corresponding to the first port, and turning off other receivers than the first receiver of the OLT. The OLT is further used for sending a control command to the ONU or the ONT, the control command being used for instructing the ONU or the ONT to turn off a wavelength stabilizing device of a transmitter of the ONU or the ONT. The ONU is used for receiving the control command from the OLT and turning off the wavelength stabilizing device of the transmitter.

Description

Optical line terminal, optical network unit and passive optical network system

Technical field

The present invention relates to the field of optical communications, and in particular to an optical line terminal OLT, an optical network unit, and a passive optical network system in the field of optical communications.

Background technique

With the rapid development of optical communication technologies, Passive Optical Network ("PON") systems are increasingly used in optical communication technologies. As shown in FIG. 1 , the PON system may include: an optical line terminal (“OLT”) located at the central office, and an optical distribution network (ODN) including a passive optical device. And an optical network unit (Operation Network Unit (ONU)/Optical Network Terminal (ONT)), where the ONU can be used to refer to the ONU and/or the ONT. In the PON system, the transmission from the OLT to the ONU/ONT direction is called downlink, and vice versa. The downlink data is broadcasted by the OLT to each ONU because of the characteristics of the optical. The uplink data transmission of each ONU is allocated by the OLT. The uplink direction uses time division multiplexing transmission. The ODN is a passive optical splitting device, and transmits the downlink data of the OLT to each ONU. At the same time, the uplink data of the multiple ONUs is collectively transmitted to the OLT; the ONU provides a user-side interface for the PON system, and the uplink is connected to the ODN. ODN is generally divided into three parts: passive optical splitter Splitter, backbone fiber, and branch fiber. For a typical PON system, the upstream and downstream use a different wavelength.

Time Wavelength Division Multiplexing (TWDM-PON) is an extension of the above PON architecture. TWDM is an abbreviation of Time Division Multiplexing (TDM) and Wavelength Division Multiplexing (WDM). The same point as the PON architecture is that the entire ODN network structure is unchanged. The main difference is that the number of uplink and downlink wavelengths is increased from one to four or more, as shown in FIG. 2 . In the downstream direction, the four transmitters at the OLT end respectively emit four different wavelengths, pass through the combiner, enter the backbone fiber, and then reach the ONU. For the receiver of the ONU, only one of the wavelengths is selected for reception, so it is necessary to add a filter before the receiver; One of the four wavelengths is selected, so different ONUs can prepare four different filters; a tunable filter can also be selected, which is configured to different wavelengths according to actual needs, thereby reducing the type of filter. In the upstream direction, any ONU also emits one of four upstream wavelengths, so there are four kinds of upstream light at any one time. Like the filter, this transmitter can be used with four different lasers or a tunable laser that can be adjusted to a specific wavelength as needed to reduce the number of ONUs. After the four wavelengths of the uplink enter the ODN, they reach the splitter of the OLT. The splitter separates the upstream light of four different wavelengths into different receivers. The wavelength division multiplexer WDM at the OLT and the ONU is a filter for concentrating or separating the upstream and downstream wavelengths.

The traffic of the user in the access network may be significantly different in different time periods. For the TWDM-PON system, multiple wavelength channels are stacked in each ODN, and the system will open all channels when the traffic is large, but the traffic is low. Or when the number of users is small, the operator usually chooses to close some of the channel ports and only open one or a few channels to save energy. However, the traditional TWDM-PON energy-saving method can only save the power consumption of the OLT and the power consumption of the ONU in the sleep mode. For the ONU of the TWDM-PON, the channel planning of the dense wavelength division is required, and both ends of the ONU transceiver need to be used. The upstream and downstream wavelengths are stably controlled. The common upstream wavelength requires TEC stable wavelength. The downstream requires a heater or TEC stable downlink adjustable receiver. The wavelength stability control loop often occupies the most important power consumption of the optical module.

There is no effective energy saving method or architecture for TWDM-PON ONUs in the prior art.

Summary of the invention

In view of this, the embodiment of the present invention provides a TWDM-PON architecture for achieving better and more efficient energy saving in the case of less user traffic or initial deployment of the system.

The first aspect provides a time division wavelength division multiplexing passive optical network TWDM-PON system, including an optical line terminal OLT, an optical distribution network ODN, and at least one optical network unit ONU, including the OLT including a wavelength adjustable point a wavelength tunable splitter having a common port and four branch ports; the OLT for controlling the wavelength tunable splitter such that all are transmitted from the ONU and are The optical signals entering the common port of the diplexer are all demultiplexed to the first port of the four branch ports, enter the first receiver corresponding to the first port, and close the OLT. a receiver other than a receiver; the OLT is also used for Sending a control command to the ONU, the control command is used to instruct the ONU to turn off the wavelength stabilization device of its transmitter; the ONU is configured to receive a control command from the OLT, and turn off the wavelength stabilization device of the transmitter.

In conjunction with the first aspect, in a first possible implementation of the first aspect, the wavelength tunable splitter comprises a wavelength tunable wavelength division multiplexer and a fixed wavelength splitter.

In conjunction with the first aspect, in a second possible implementation of the first aspect, the wavelength tunable splitter comprises a straight waveguide and three adjustable microring filters.

In conjunction with the first possible implementation of the first aspect, in a third possible implementation of the first aspect, the wavelength tunable splitter includes a transmissive port and a reflective port, and the transmissive port transmits The bandwidth width is at least a wavelength interval of the second wavelength to the fourth wavelength in the TWDM-PON system.

In conjunction with the third possible implementation of the first aspect, in a fourth possible implementation of the first aspect, the OLT is configured to control the wavelength tunable splitter such that all are transmitted from the ONU The optical signals entered by the common port of the wavelength tunable splitter are all demultiplexed to the first port of the four branch ports, and enter the first receiver corresponding to the first port, and the a receiver other than the first receiver of the OLT, specifically comprising the OLT adjusting a transmission band of the wavelength tunable splitter to be outside a transmission band of the ONU transmitter; when the ONU transmitter transmits Any wavelength within the range of the emission band, the arbitrary wavelength passing through the wavelength tunable splitter, and exiting from the reflective port.

In conjunction with the second possible implementation of the first aspect, in a fifth possible implementation manner of the first aspect, the OLT is configured to control the wavelength tunable splitter so that all are transmitted from the ONU The optical signals entered by the common port of the wavelength tunable splitter are all demultiplexed to the first port of the four branch ports, and enter the first receiver corresponding to the first port, and the The receiver of the OLT except the first receiver specifically includes the OLT adjusting the center wavelength of the three micro-loop filters of the wavelength-tunable splitter to be outside the range of the emission band of the ONU transmitter, Or the OLT turns off the three micro-ring filters; when the ONU transmitter is at any wavelength within its transmission band, the arbitrary wavelength passes through the wavelength-tunable demultiplexer and is emitted from the same port.

In conjunction with the first aspect and any one of the possible implementations of the first aspect, in a sixth possible implementation of the first aspect, the ONU includes a dual band tunable filter and an optical receiver.

In conjunction with the sixth possible implementation of the first aspect, in a seventh possible implementation of the first aspect, the dual-band tunable filter includes two transmission bands, wherein a wide-spectrum transmission band and a Narrow-spectrum transmission band.

In conjunction with the sixth or seventh possible implementation of the first aspect, in an eighth possible implementation of the first aspect, the ONU is configured to receive a control command from the OLT, and turn off a wavelength of the transmitter a stabilizing device, specifically comprising: when the ONU receives a control command from the OLT, setting a temperature of the dual band tunable filter to a current ambient temperature, and turning off the temperature control device of the dual band tunable filter .

In a second aspect, an optical line terminal OLT includes a processor, four receivers, and a wavelength tunable splitter, wherein the wavelength tunable splitter has a common port and four branch ports, and the fourth Each of the branch ports is connected to the four receivers; the processor of the OLT is configured to control the wavelength tunable splitter such that it is transmitted from the ONU and enters by a common port of the wavelength tunable splitter The optical signals are all demultiplexed to the first port of the four branch ports, enter the first receiver corresponding to the first port, and close other receivers of the OLT except the first receiver The processor of the OLT is further configured to send a control command to the ONU, the control command is used to instruct the ONU to turn off the wavelength stabilization device of its transmitter.

In conjunction with the second aspect, in a first possible implementation of the second aspect, the wavelength tunable splitter comprises a wavelength tunable wavelength division multiplexer and a fixed wavelength splitter.

In conjunction with the second aspect, in a second possible implementation of the second aspect, the wavelength tunable splitter comprises a straight waveguide and three adjustable microring filters.

In conjunction with the first possible implementation of the second aspect, in a third possible implementation of the second aspect, the wavelength tunable splitter includes a transmissive port and a reflective port, and the transmissive port transmits The bandwidth width is at least a wavelength interval of the second wavelength to the fourth wavelength corresponding to the second receiver of the OLT and the fourth receiver.

In conjunction with the second aspect, in a fourth possible implementation of the second aspect, the OLT a processor for controlling the wavelength tunable splitter such that optical signals transmitted from the ONU and accessed by a common port of the wavelength tunable splitter are all demultiplexed to a first of the four branch ports a port that enters a first receiver corresponding to the first port, turns off a receiver other than the first receiver of the OLT, and specifically includes a processor of the OLT to adjust the wavelength-tunable splitting The transmission of the device is outside the emission band of the ONU transmitter; after receiving any wavelength of the ONU transmitted within the range of its emission band through the wavelength tunable demultiplexer, the arbitrary wavelength is from the The reflective port exits; the processor of the OLT controls to turn off other receivers than the first receiver connected to the reflective port.

With reference to the second aspect, in a fifth possible implementation manner of the second aspect, the processor of the OLT is configured to control the wavelength tunable splitter so that the signal is transmitted from the ONU and is tunable by the wavelength The optical signals entering by the common port of the wave device are all demultiplexed to the first port of the four branch ports, enter the first receiver corresponding to the first port, and close the first receiving of the OLT The receiver other than the machine includes: the processor of the OLT adjusts a center wavelength of three micro-loop filters of the wavelength-tunable splitter to be outside a range of a transmission band of the ONU transmitter, or The OLT turns off the three micro-ring filters by current injection; when receiving any wavelength in the range of its emission band that is transmitted by the ONU, passes through the wavelength-adjustable demultiplexer, and then ejects from the same port;

The processor of the OLT controls to turn off other receivers than the first receiver connected to the same port.

In a third aspect, a tunable receiver includes a dual band tunable filter and an optical receiver, wherein the dual band tunable filter includes two transmission bands, wherein a wide spectrum transmission band and a Narrow-spectrum transmission band.

With reference to the third aspect, in a first possible implementation manner of the third aspect, when the ONU receives the control command from the optical line terminal OLT, the temperature of the dual-band tunable filter is set to the current The ambient temperature is turned off by the temperature control device of the dual band tunable filter.

A fourth aspect, an optical network unit ONU, comprising a tunable receiver, wherein the tunable receiver comprises the tunable receiver of the third aspect or the first possible implementation of the third aspect .

In a fifth aspect, a time division wavelength division multiplexing TWDM-PON system includes an optical line terminal OLT, an optical distribution network ODN, and at least one optical network unit ONU, including: the OLT includes a wavelength tunable splitter, The wavelength tunable splitter has a common port and four branch ports; the OLT is configured to control the wavelength tunable splitter such that all are transmitted from the ONU and are common to the wavelength tunable splitter The optical signals entering the port are all demultiplexed to the first port of the four branch ports, and enter the first receiver corresponding to the first port; the ONU is used to adjust the wavelength of the transmitter to the first a wavelength, wherein the first wavelength corresponds to the first port.

In conjunction with the fifth aspect, in a first possible implementation of the fifth aspect, the wavelength tunable splitter comprises a wavelength tunable wavelength division multiplexer and a fixed wavelength splitter.

In conjunction with the fifth aspect, in a second possible implementation of the fifth aspect, the wavelength tunable splitter comprises a straight waveguide and three adjustable microring filters.

In conjunction with the first possible implementation of the fifth aspect, in a third possible implementation manner of the fifth aspect, the wavelength tunable splitter includes a transmissive port and a reflective port, and the transmissive port transmits The bandwidth width is at least a wavelength interval of the second wavelength to the fourth wavelength in the TWDM-PON system.

With reference to the third possible implementation manner of the fifth aspect, in a fourth possible implementation manner of the fifth aspect, the OLT is configured to control the wavelength tunable splitter so that all from the ONU or the ONT The optical signals transmitted and entered by the common port of the wavelength tunable splitter are all demultiplexed to the first port of the four branch ports, and enter the first receiver corresponding to the first port, Specifically, the OLT adjusts a transmission band of the wavelength tunable splitter to be outside a transmission band of the ONU transmitter; when the ONU transmitter transmits any wavelength within a range of its emission band, the arbitrary wavelength After passing through the wavelength tunable splitter, it exits from the reflective port.

With reference to the second possible implementation manner of the fifth aspect, in a fifth possible implementation manner of the fifth aspect, the OLT is configured to control the wavelength tunable splitter so that all from the ONU or the ONT The optical signals transmitted and entered by the common port of the wavelength tunable splitter are all demultiplexed to the first port of the four branch ports, and enter the first receiver corresponding to the first port, Specifically, the OLT adjusts a center wavelength of three micro-loop filters of the wavelength-tunable demultiplexer to a range outside a transmission band of the ONU transmitter, or the OLT passes a current injection The input mode turns off the three micro-ring filters; when the ONU transmitter is at any wavelength within its transmission band, the arbitrary wavelength passes through the wavelength-tunable demultiplexer and is emitted from the same port.

The TWDM-PON architecture proposed by the present invention can turn off the temperature device of the ONU (or may also be referred to as a wavelength adjustment device) when the TWDM-PON user traffic is low and the traffic volume at the initial stage of system deployment is low, thereby achieving better performance. System energy saving.

DRAWINGS

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the embodiments of the present invention will be briefly described below. It is obvious that the drawings described below are only some embodiments of the present invention, Those skilled in the art can also obtain other drawings based on these drawings without paying any creative work.

1 is a schematic diagram of a PON structure of a passive optical network;

2 is a schematic structural diagram of a TWDM-PON network;

FIG. 3 is a schematic structural diagram of an energy-saving PON network according to Embodiment 1 of the present invention; FIG.

FIG. 3b is a schematic structural diagram of an optical line terminal OLT according to an embodiment of the present disclosure;

3c is a schematic structural diagram of an adjustable receiver on an ONU side according to an embodiment of the present invention;

4 is a schematic diagram of functions of a wavelength tunable splitter according to an embodiment of the present invention;

FIG. 5 is a schematic structural diagram of an implementation of a first wavelength tunable splitter according to an embodiment of the present invention; FIG.

6 is a schematic structural diagram of an implementation of a second wavelength tunable splitter according to an embodiment of the present invention;

FIG. 7 is a schematic diagram of a TWDM-PON system for fast channel switching according to an embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are a part of the embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of the present invention.

2 is a schematic diagram of a network architecture of a TWDM-PON system. As shown in FIG. 2, the TWDM-PON system 100 includes an OLT 110, a plurality of ONUs 120, and an Optical Distribution Network (ODN) 130, wherein the OLT 110 passes ODN 130 with a point-to-multipoint Connect to multiple ONUs 120. More than one OLT may also be included in the TWDM-PON system 100. The plurality of ONUs 120 share an optical transmission medium of the ODN 130. The ODN 130 may include a backbone fiber 131, an optical power split module 132, and a plurality of branch fibers 133. The optical power splitting module 132 may be disposed at a remote node (Remote Node, hereinafter referred to as RN), which is connected to the OLT 110 through the trunk optical fiber 131 on the one hand, and connected to the plurality of ONUs 120 through the plurality of branch optical fibers 133 on the other hand. In the TWDM-PON system 100, the communication link between the OLT 110 and the plurality of ONUs 120 may include a plurality of wavelength channels that share the optical transmission medium of the ODN 130 by WDM. Each ONU 120 can operate in one of the wavelength channels of the TWDM-PON system 100, and each wavelength channel can carry the traffic of one or more ONUs 120. Moreover, the ONU 120 operating in the same wavelength channel can share the wavelength channel by TDM. In FIG. 2, the TWDM-PON system 100 has four wavelength channels as an example. It should be understood that, in practical applications, the number of wavelength channels of the TWDM-PON system 100 may also be determined according to network requirements.

For convenience of description, in FIG. 2, the four wavelength channels of the TWDM-PON system 100 are respectively named as wavelength channel 1, wavelength channel 2, wavelength channel 3, and wavelength channel 4, wherein each wavelength channel adopts a pair of uplink and downlink wavelengths respectively. For example, the upstream wavelength and the downstream wavelength of the wavelength channel 1 may be λu1 and λd1, respectively, and the upstream wavelength and the downstream wavelength of the wavelength channel 2 may be λu2 and λd2, respectively, and the upstream wavelength and the downstream wavelength of the wavelength channel 3 may be λu3 and λd3, respectively. The upstream wavelength and the downstream wavelength of the wavelength channel 4 may be λu4 and λd4, respectively. Each wavelength channel can have a corresponding wavelength channel identifier (for example, the channel numbers of the four wavelength channels can be 1, 2, 3, and 4 respectively), that is, the wavelength channel identifier matches the uplink and downlink wavelengths of the wavelength channel identified by the wavelength channel. Relationships, OLT 110 and ONU 120 can learn the upstream and downstream wavelengths of the wavelength channel based on the wavelength channel identification.

The OLT 110 may include an optical coupler 111, a first wavelength division multiplexer 112, a second wavelength division multiplexer 113, a plurality of downstream optical transmitters Tx1 to Tx4, a plurality of upstream optical receivers Rx1 to Rx4, and a processing module 114. . The plurality of downstream optical transmitters Tx1 to Tx4 are connected to the optical coupler 111 through the first wavelength division multiplexer 112, and the plurality of upstream optical receivers Rx1 to Rx4 are connected to the optical coupler through the second wavelength division multiplexer 113. 111, the coupler 111 is further connected to the trunk fiber 131 of the ODN 130.

The emission wavelengths of the plurality of downstream light emitters Tx1 to Tx4 are different, wherein each of the descending lights The transmitters Tx1 to Tx4 may respectively correspond to one of the wavelength channels of the TWDM-PON system 100. For example, the emission wavelengths of the plurality of downlink light emitters Tx1 to Tx4 may be respectively λd1 to λd4. The downstream optical transmitters Tx1 to Tx4 can respectively transmit downlink data to corresponding wavelength channels by using their emission wavelengths λd1 ～ λd4 to be received by the ONUs 120 operating in the corresponding wavelength channels. Correspondingly, the receiving wavelengths of the plurality of uplink optical receivers Rx1 to Rx4 may be different, and each of the upstream optical receivers Rx1 to Rx4 also respectively correspond to one of the wavelength channels of the TWDM-PON system 100, for example, multiple uplinks. The receiving wavelengths of the optical receivers Rx1 to Rx4 may be λu1 to λu4, respectively. The upstream optical receivers Rx1 to Rx4 can receive the uplink data transmitted by the ONU 120 operating in the corresponding wavelength channel by using the reception wavelengths λu1 to λu4, respectively.

The first wavelength division multiplexer 112 is configured to perform wavelength division multiplexing processing on downlink data of wavelengths λd1 ～ λd4 respectively emitted by the plurality of downlink optical transmitters Tx1 TTx4, and transmit the optical fibers to the trunk optical fiber of the ODN 130 through the optical coupler 111. 131 to provide downlink data to the ONU 120 through the ODN 130. Moreover, the optical coupler 111 can also be used to provide uplink data from the plurality of ONUs 120 and having wavelengths of λu1 to λu4, respectively, to the second wavelength division multiplexer 113, and the second wavelength division multiplexer 113 can respectively set the wavelengths to The uplink data of λu1 to λu4 is demultiplexed to the upstream optical receivers Rx1 to Rx4 for data reception.

The processing module 114 may be a Media Access Control (MAC) module, which may specify a working wavelength channel for the plurality of ONUs 120 by wavelength negotiation, and according to the working wavelength channel of a certain ONU 120, is to be sent to The downlink data of the ONU 120 is provided to the downlink optical transmitters Tx1 to Tx4 corresponding to the wavelength channels, so that the downlink optical transmitters Tx1 to Tx4 transmit the downlink data to the corresponding wavelength channels. On the other hand, the processing module 114 can also apply the respective wavelengths. The dynamic bandwidth allocation (Dynamic Bandwidth Allocation, DBA for short) of the channel is allocated to the ONU 120 multiplexed to the same wavelength channel by the TDM mode to allocate the uplink transmission time slot to authorize the ONU 120 to pass the corresponding time slot in the specified time slot. The wavelength channel transmits uplink data.

The uplink transmit wavelength and the downlink receive wavelength of each ONU 120 are adjustable, and the ONU 120 can adjust its own uplink transmit wavelength and downlink receive wavelength to the upstream and downstream wavelengths of the wavelength channel according to the wavelength channel specified by the OLT 110, respectively. Therefore, transmission and reception of uplink and downlink data through the wavelength channel are implemented. For example, if OLT 110 indicates that an ONU 120 is operating to wavelength channel 1 during wavelength negotiation, ONU 120 may have its own upstream transmit wavelength. And the downlink receiving wavelength is respectively adjusted to the first uplink wavelength λu1 and the first downlink wavelength λd1; if the OLT 110 instructs the ONU 120 to operate to the wavelength channel 3, the ONU 120 can adjust its own uplink transmitting wavelength and downlink receiving wavelength to the first The three upstream wavelengths λu3 and the first downstream wavelength λd3.

The ONU 120 can include an optocoupler 121, a downstream optical receiver 122, an upstream optical transmitter 123, and a processing module 124. The downstream optical receiver 122 and the upstream optical transmitter 123 are connected to the branch optical fiber 133 corresponding to the ONU 120 through the optical coupler 121. The optical coupler 121 can provide the uplink data sent by the upstream optical transmitter 123 to the branch fiber 133 of the ODN 130 on the one hand for transmission to the OLT 110 through the ODN 130; on the other hand, the optical coupler 121 can also pass the OLT 110 through the ODN. The downlink data transmitted by 130 is provided to the downstream optical receiver 122 for data reception.

The processing module 124 can be a MAC module, which can perform wavelength negotiation with the OLT 110, and adjust the receiving wavelength of the downstream optical receiver 122 and the transmitting wavelength of the upstream optical transmitter 123 according to the wavelength channel specified by the OLT 110 (ie, adjusting the ONU 120). The downlink receiving wavelength and the uplink transmitting wavelength are configured to enable the ONU 120 to operate at a wavelength channel designated by the OLT 110. In addition, the processing module 124 can also control the uplink optical transmitter 123 to transmit in the designated time slot according to the dynamic bandwidth allocation result of the OLT 110. Upstream data.

The embodiment of the present invention provides an energy-saving TWDM-PON system, including an OLT, an ODN, and an ONU, as shown in FIG. 3a, specifically:

The OLT includes a wavelength tunable splitter having a common port and four branch ports; the OLT is configured to control the wavelength tunable splitter such that all are transmitted from the ONU And the optical signals entered by the common port of the wavelength tunable splitter are all demultiplexed to the first port of the four branch ports, and then enter the first receiver corresponding to the first port, Turning off the receiver of the OLT other than the first receiver; the OLT is further configured to send a control command to the ONU, the control command is used to instruct the ONU to turn off the wavelength stabilization device of the transmitter; The ONU is configured to receive a control command from the OLT and turn off the wavelength stabilization device of the transmitter. Please refer to the subsequent instructions for specific content.

In addition, an embodiment of the present invention further provides an optical line terminal OLT, as shown in FIG. 3b, including a processor, four receivers, and a wavelength tunable splitter, wherein the wavelength tunable splitter has a common a port and four branch ports, the four branch ports being connected to the four receivers;

Specifically, the processor of the OLT is configured to control the wavelength tunable splitter such that optical signals transmitted from the ONU and accessed by a common port of the wavelength tunable splitter are all demultiplexed into the a first port of the four branch ports, entering a first receiver corresponding to the first port, and turning off other receivers of the OLT other than the first receiver;

The processor of the OLT is further configured to send a control command to the ONU, the control command is used to instruct the ONU to turn off the wavelength stabilization device of its transmitter. Please refer to the subsequent instructions for specific content.

In addition, an embodiment of the present invention further provides an energy-saving tunable receiver, the tunable receiver being disposed in an ONU, as shown in FIG. 3c, the tunable receiver includes a dual-band tunable filter and a light receiving machine. The tunable filter has two transmission bands, a wide spectral transmission band and a narrow spectral transmission band, and the transmission curve of the filter can change as the filter temperature changes. The tunable filter is also provided with a temperature control device, such as (Thermo Electric Cooler, TEC for short) or a heater, whose operating temperature can be controlled by the ONU optical module. The broad-spectrum transmission band as shown in Figure 7 allows multiple wavelengths to be transmitted over a wide range and temperature range, while a narrow-spectrum transmission band allows only one wavelength to pass through the filter. In order to achieve better energy saving, the tunable filter can be designed to have an ambient temperature range (for example, 0 to 70 degrees) in which the entire optical module operates normally, and a wide-spectrum transmission band can allow one of the wavelengths (for example, wavelength). 1) or multiple wavelengths (for example, wavelength 1 to wavelength 4) are transmitted through the filter, and the temperature of the tunable filter allows only a certain wavelength to be transmitted through at a high temperature, for example, the wavelength 1 is allowed to pass through at a temperature of T1, at a temperature of T2. Wavelength 2 is allowed to pass through, wavelength 3 is allowed to pass through at T3 temperature, and wavelength 4 is allowed to pass through at T4 temperature.

At this time, if the ONU informs through the message sent by the OLT or it detects that only one wavelength in the current system is working (when the total traffic of the system is low or the number of users is small), it can be under the command of the OLT. Or set the temperature of the tunable filter to the current ambient temperature and turn off the temperature control device of the tunable filter to make the temperature match the ambient temperature, thus saving energy.

In addition, the tunable receiver can achieve wide spectrum reception and narrow spectrum reception, so it can be used as an ONU of TWDM-PON based on optical splitter ODN, and can also be used as a wavelength division multiplexer based ODN. WDM-PON ONU.

In addition, an embodiment of the present invention further provides an optical network unit ONU, including a tunable receiver. The internal structure of the tunable receiver is as described in the above embodiment.

The TWDM-PON system or OLT device and the wavelength tunable splitter in the above embodiment will be further explained below. The details are as follows:

As shown in FIG. 3a, FIG. 3a is an energy-saving TWDM-PON network architecture provided by the implementation of the present invention. The main difference between the PON architecture and the TWDM-PON network shown in FIG. 2 is that the OLT includes a wavelength-tunable splitter having a common port and four branch ports. The wavelength tunable splitter has two operating states, and the state is as shown in FIG. 3a(a). In this state, the branch port 1 has no wavelength selectivity, and any wavelength in the range of wavelengths λ1 λ λ4 When the public port enters, the branch port 1 will exit. State 2 is shown in Figure 3a (b), the optical signals λ1, λ2, λ3, λ4 of different wavelengths incident from the common port are sequentially demultiplexed to the port 1, port 2, port 4 of the wavelength tunable splitter. .

When the TWDM-PON system is in normal working state, assuming that the capacity of each wavelength channel is 10 Gb/s (gigabits per second), a total of four wavelength channels are set on the OLT side, and the wavelength-tunable splitter on the OLT side is in the figure. State 2 in 3a(b), which can normally demultiplex the optical signals of wavelength 1 to wavelength 4 transmitted by the ONU to the OLT to the receiver 1, receiver 2, receiver 3, and receiver of the four channels of the OLT. In machine 4, the entire system can provide users with a maximum bandwidth capacity of a total of 40 Gb/s. When the number of users in the initial stage of system deployment is small or the traffic of users in the middle of the night is small, only one wavelength channel is required to provide 10Gb/s bandwidth to meet the bandwidth requirements of all users. At this time, the OLT can adjust the wavelength in Figure 3a. The splitter is adjusted to state 1 such that all optical signals transmitted from the ONU and entered by the common port of the wavelength tunable splitter are demultiplexed to port 1 (or port 2, or port 3, or port 4) and Entering the receiver 1 (or receiver 2, or receiver 3, or receiver 4) of the OLT, then the OLT turns off the other receivers. At this time, since the wavelength tunable splitter on the OLT side can demultiplex any wavelength of the ONU allowed transmission band range into the receiver 1, the ONU transmitter does not need to precisely control its emission wavelength at this time, so the OLT can The energy stabilizing device is turned off by turning off the wavelength stabilization device of the ONU transmitter, for example, turning off the thermoelectric cooler TEC or heater in the ONU transmitter for stabilizing the temperature of the transmitter, and its control circuit.

It should be noted that, in the traditional TWDM-PON, there are 4 uplink and downlink in the system. The wavelength, so each ONU's transmitter can only transmit one of the wavelengths stably. Since the four wavelengths in the system are very close together, for example, usually only 100 GHz (gihs), in order to avoid crosstalk to other channels, The transmitter of the ONU must control its transmission wavelength very stably, and the transmission wavelength of the traditional transmitter will drift with the temperature. Therefore, the common TWDM-PON ONU transmitter must use a special temperature control device. (Also known as a wavelength stabilization device), such as a semiconductor cooler TEC, a heater, or the like. The temperature control device stabilizes the temperature of the transmitter at a constant temperature, and this temperature control device tends to occupy a large part of the power consumption of the optical module. With the system structure provided by the present invention, the number of users in the initial stage of system deployment is small or the amount of services of users in the middle of the night is small. Only when one wavelength channel provides 10 Gb/s bandwidth to meet the bandwidth requirements of all users, the ONU can be turned off. The temperature control device of the transmitter allows it to operate in an uncooled mode, thus saving the power consumption of the ONU optical module to a large extent.

4 shows a functional diagram of the wavelength tunable splitter, and the wavelength tunable splitter shown in FIG. 4 can be implemented in various structures. As shown in FIG. 5, FIG. 5 shows an implementation structure of a wavelength tunable splitter. The wavelength tunable splitter comprises a wavelength tunable wavelength division multiplexer and a fixed wavelength splitter, the wavelength tunable splitter comprising a transmissive port and a reflective port, the transmissive port having a transmission bandwidth width of at least The wavelength interval from wavelength 2 to wavelength 4. When the transmission band of the wavelength tunable splitter is adjusted to the center of the wavelength 2 to the wavelength 4, the wavelength 1 is emitted from the reflection port of the wavelength tunable splitter into the port 1, and the

wavelengths

2, 3, 4 can be from the wavelength. The transmission port of the tunable wavelength division multiplexer 1 exits, then enters the common port of the fixed wavelength splitter 2, and then demultiplexes it to the three ports of the fixed wavelength splitter (in turn, the port in FIG. 5) 2, 3, 4). When the transmission band of the wavelength tunable splitter is adjusted to be outside the emission band S of the ONU transmitter, when the ONU transmitter is at any wavelength within the range of its emission band S (including any wavelength between wavelength and wavelength 4), Both are demultiplexed by the wavelength tunable wavelength division multiplexer 1 to its reflection port and exit from port 1.

As shown in FIG. 6, FIG. 6 shows an implementation structure of still another wavelength tunable splitter. The wavelength tunable splitter comprises a straight waveguide and three adjustable microring filters. When the transmission wavelengths of the three microring filters are adjusted to wavelength 2, wavelength 3, and wavelength 4, respectively, The tuned wave splitter can demultiplex wavelength 2, wavelength 3, and wavelength 4 onto

ports

2, 3, and 4 in sequence, and the remaining wavelength 1 is emitted from port 1. When the center wavelength of the three micro-loop filters is adjusted to the emission band of the ONU transmitter Outside the S range or three micro-ring filters are turned off by current injection, etc., when the ONU transmitter is at any wavelength within the range of its emission band S (including any wavelength between wavelength 1 and wavelength 4), Will exit directly from port 1.

The above description of the wavelength tunable splitter can be applied to the system or OLT device described in the first embodiment or the second embodiment.

An embodiment of the present invention provides a fast wavelength switching TWDM-PON system, where the PON system includes an OLT, an ODN, and an ONU, the OLT includes a wavelength tunable splitter, and the wavelength tunable splitter has a a common port and four branch ports; the OLT is configured to control the wavelength tunable splitter such that all optical signals transmitted from the ONU and accessed by a common port of the wavelength tunable splitter are completely resolved Using a first port of the four branch ports to enter a first receiver corresponding to the first port; the ONU is configured to adjust a wavelength of the transmitter to a first wavelength, wherein the first wavelength is The first port corresponds.

Specifically, FIG. 7 is a schematic diagram of fast wavelength switching of a TWDM-PON system according to an embodiment of the present invention. The structure is exactly the same as that in the first embodiment. In other ports (ports 2 to 4), the transmission failure needs to be repaired or needs to be upgraded. When all users need to be quickly switched to one channel, the adjustable demultiplexer in FIG. 7 can be directly used. The state is switched from state 2 to state 1, then all ONUs are switched to channel 1 at this time, after which the ONU can gradually adjust the wavelength of the ONU transmitter to wavelength 1, since the adjustable splitter can receive the ONU at this time. The transmission of any wavelength in the wavelength range, so when the subsequent adjustment of the ONU's emission wavelength, the service will not be interrupted, the terminal time of the service only depends on the adjustment time of the adjustable demultiplexer. In contrast, the traditional channel switching method is to switch the wavelength of each ONU to a new destination channel, mainly depending on the channel time of the slowest ONU. The switching time of the invention only depends on the switching speed of the adjustable splitter on the OLT side, and the device on the OLT side is shared by all ONUs, which can be designed to adjust the faster device, thereby speeding up the switching of the ONU channel. Time, realize a TWDM-PON system in which the wavelength is quickly switched to the destination channel.

The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any equivalent person can be easily conceived within the technical scope of the present invention by any person skilled in the art. Modifications or substitutions, which should be covered by the scope of protection of the present invention within. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

A time division wavelength division multiplexing passive optical network TWDM-PON system, comprising an optical line terminal OLT, an optical distribution network ODN, and at least one optical network unit ONU, comprising:

The OLT includes a wavelength tunable splitter, the wavelength tunable splitter having a common port and four branch ports;

The OLT is configured to control the wavelength tunable splitter such that all optical signals transmitted from the ONU and accessed by a common port of the wavelength tunable splitter are demultiplexed to the four branch ports a first port in the first port, entering a first receiver corresponding to the first port, and closing a receiver other than the first receiver of the OLT;

The OLT is further configured to send a control command to the ONU, where the control command is used to instruct the ONU to turn off a wavelength stabilization device of its transmitter;

The ONU is configured to receive a control command from the OLT to turn off the wavelength stabilization device of the transmitter.
The system of claim 1 wherein said wavelength tunable splitter comprises a wavelength tunable wavelength division multiplexer and a fixed wavelength splitter.
The system of claim 1 wherein said wavelength tunable splitter comprises a straight waveguide and three adjustable microring filters.
The system of claim 2 wherein said wavelength tunable splitter comprises a transmissive port and a reflective port, said transmissive port having a transmission bandwidth width of at least a second of said TWDM-PON system The wavelength interval from the wavelength to the fourth wavelength.
The system of claim 4 wherein said OLT is operative to control said wavelength tunable splitter such that all common ports transmitted from said ONU or ONT and by said wavelength tunable splitter The incoming optical signals are all demultiplexed to the first port of the four branch ports, and the first receiver corresponding to the first port is included, which specifically includes:

The OLT adjusts a transmission band of the wavelength tunable splitter to be outside a transmission band of the ONU transmitter;

When the ONU transmitter transmits any wavelength within its range of transmission wavelengths, the arbitrary wavelength passes through the wavelength tunable splitter and exits from the reflective port.
The system of claim 3 wherein said OLT is operative to control said wavelength tunable splitter such that all common ports transmitted from said ONU or ONT and by said wavelength tunable splitter The incoming optical signals are all demultiplexed to the first port of the four branch ports, and the first receiver corresponding to the first port is included, which specifically includes:

The OLT adjusts a center wavelength of three micro-loop filters of the wavelength-tunable demultiplexer to a range outside a transmission band of the ONU transmitter, or the OLT turns off the three micro-ring filters;

When the ONU transmitter is at any wavelength within its range of transmission wavelengths, the arbitrary wavelength passes through the wavelength tunable splitter and is ejected from the same port.
A system according to any one of claims 1 to 6, wherein said ONU comprises a dual band tunable filter and an optical receiver.
A system according to any of the preceding claims, wherein the dual band tunable filter comprises two transmission bands, one of which is a broad spectrum transmission band and a narrow spectrum transmission band.
The system according to claim 7 or 8, wherein the ONU is configured to receive a control command from the OLT, and to turn off the wavelength stabilization device of the transmitter, specifically:

When the ONU receives a control command from the OLT, the temperature of the dual band tunable filter is set to a current ambient temperature, and the temperature control device of the dual band tunable filter is turned off.
An optical line terminal OLT, comprising:

a processor, four receivers, a wavelength tunable splitter, wherein the wavelength tunable splitter has a common port and four branch ports, the four branch ports respectively associated with the four receivers Connected

a processor of the OLT for controlling the wavelength tunable splitter such that optical signals transmitted from the ONU and entered by a common port of the wavelength tunable splitter are all demultiplexed to the four branches a first port in the port, entering a first receiver corresponding to the first port, and turning off a receiver other than the first receiver of the OLT;

The processor of the OLT is further configured to send a control command to the ONU, the control command is used to instruct the ONU to turn off the wavelength stabilization device of its transmitter.
The OLT according to claim 10, wherein said wavelength tunable splitter It includes a wavelength tunable wavelength division multiplexer and a fixed wavelength splitter.
The OLT of claim 10 wherein said wavelength tunable splitter comprises a straight waveguide and three adjustable microring filters.
The OLT according to claim 11, wherein said wavelength tunable splitter comprises a transmissive port and a reflective port, said transmissive port having a transmission bandwidth width of at least a second receiver and said OLT The wavelength interval of the second wavelength to the fourth wavelength corresponding to the four receivers.
The OLT according to claim 10, wherein the processor of the OLT is configured to control the wavelength tunable splitter such that it is transmitted from the ONU and is accessed by a common port of the wavelength tunable splitter The optical signals are all demultiplexed to the first port of the four branch ports, enter the first receiver corresponding to the first port, and close other receivers of the OLT except the first receiver Specifically, including:

The processor of the OLT adjusts a transmission band of the wavelength tunable splitter to be outside a transmission band of the ONU transmitter;

The arbitrary wavelength is emitted from the reflective port after receiving the wavelength-tunable splitter emitted by the ONU in the range of its emission band;

The processor of the OLT controls to turn off other receivers than the first receiver connected to the reflective port.
The OLT according to claim 10, wherein the processor of the OLT is configured to control the wavelength tunable splitter such that it is transmitted from the ONU and is accessed by a common port of the wavelength tunable splitter The optical signals are all demultiplexed to the first port of the four branch ports, enter the first receiver corresponding to the first port, and close other receivers of the OLT except the first receiver Specifically, including:

The processor of the OLT adjusts a center wavelength of three micro-loop filters of the wavelength-tunable splitter to be outside a range of a transmission band of the ONU transmitter, or the OLT turns off the three by current injection Microring filter

After receiving the wavelength tunable splitter emitted by the ONU in the range of its emission band, it is emitted from the same port;

The processor of the OLT controls to turn off the first receiver connected to the same port Other receivers.
A tunable receiver, characterized in that the tunable receiver comprises a dual band tunable filter and an optical receiver, wherein the dual band tunable filter comprises two transmission bands, one of which Wide spectrum transmission band and a narrow spectrum transmission band.
The tunable receiver according to claim 16, wherein when the ONU receives a control command from the optical line terminal OLT, the temperature of the dual band tunable filter is set to a current ambient temperature, The temperature control device of the dual band tunable filter is turned off.
An optical network unit ONU, comprising a tunable receiver, wherein the tunable receiver comprises the tunable receiver of claim 16 or 17.
A time division wavelength division multiplexing TWDM-PON system, comprising an optical line terminal OLT, an optical distribution network ODN, and at least one optical network unit ONU, comprising:

The OLT includes a wavelength tunable splitter, the wavelength tunable splitter having a common port and four branch ports;

The OLT is configured to control the wavelength tunable splitter such that all optical signals transmitted from the ONU and accessed by a common port of the wavelength tunable splitter are demultiplexed to the four branch ports a first port in the first port, entering a first receiver corresponding to the first port;

The ONU is configured to adjust a wavelength of its transmitter to a first wavelength, wherein the first wavelength corresponds to the first port.
The system of claim 19 wherein said wavelength tunable splitter comprises a wavelength tunable wavelength division multiplexer and a fixed wavelength splitter.
The system of claim 19 wherein said wavelength tunable splitter comprises a straight waveguide and three adjustable microring filters.
The system of claim 20 wherein said wavelength tunable splitter comprises a transmissive port and a reflective port, said transmissive port having a transmission bandwidth width of at least a second of said TWDM-PON system The wavelength interval from the wavelength to the fourth wavelength.
The system of claim 22 wherein said OLT is operative to control said wavelength tunable splitter such that all common ports transmitted from said ONU or ONT and by said wavelength tunable splitter The incoming optical signals are all demultiplexed to the first of the four branch ports The first receiver that corresponds to the first port includes:

The OLT adjusts a transmission band of the wavelength tunable splitter to be outside a transmission band of the ONU transmitter;

When the ONU transmitter transmits any wavelength within its range of transmission wavelengths, the arbitrary wavelength passes through the wavelength tunable splitter and exits from the reflective port.
The system of claim 21 wherein said OLT is operative to control said wavelength tunable splitter such that all common ports transmitted from said ONU or ONT and by said wavelength tunable splitter The incoming optical signals are all demultiplexed to the first port of the four branch ports, and the first receiver corresponding to the first port is included, which specifically includes:

The OLT adjusts a center wavelength of three micro-loop filters of the wavelength-tunable splitter to be outside a range of a transmission band of the ONU transmitter, or the OLT turns off the three micro-ring filters by a current injection manner Device

When the ONU transmitter is at any wavelength within its range of transmission wavelengths, the arbitrary wavelength passes through the wavelength tunable splitter and is ejected from the same port.