CN105721098B - The OLT in the symmetrical TWDM PON systems of high-speed transfer is realized with low speed optical device - Google Patents
The OLT in the symmetrical TWDM PON systems of high-speed transfer is realized with low speed optical device Download PDFInfo
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- CN105721098B CN105721098B CN201610064610.7A CN201610064610A CN105721098B CN 105721098 B CN105721098 B CN 105721098B CN 201610064610 A CN201610064610 A CN 201610064610A CN 105721098 B CN105721098 B CN 105721098B
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0227—Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation
- H04J14/0238—Wavelength allocation for communications one-to-many, e.g. multicasting wavelengths
- H04J14/0239—Wavelength allocation for communications one-to-many, e.g. multicasting wavelengths in WDM-PON sharing multiple downstream wavelengths for groups of optical network units [ONU], e.g. multicasting wavelengths
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- H—ELECTRICITY
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
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- H04B10/501—Structural aspects
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- H04B10/504—Laser transmitters using direct modulation
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Abstract
The invention discloses the OLT in a kind of symmetrical TWDM PON systems that high-speed transfer is realized with low speed optical device, it is related to fiber optic communication field.The OLT includes the first media control module, downlink data transmitter module, the first light wavelength division multiplexing and upstream data receiving module, and the up, descending of OLT shares the first light wavelength division multiplexing, the first media control module；Down direction, the first media control module, downlink data transmitter module, the first light wavelength division multiplexing are sequentially connected with；Up direction, the first light wavelength division multiplexing, upstream data receiving module, the first media control module are sequentially connected with.The present invention can significantly reduce the cost of system, effectively reduce the complexity of system, reduce the difficulty of system high-speed real-time transmission data.
Description
Technical field
The present invention relates to fiber optic communication field, it is specifically related to a kind of realize the symmetrical of high-speed transfer with low speed optical device
OLT in TWDM-PON systems.
Background technology
As country widelys popularize " internet+" policy, internet will welcome the high speed development of a new round, at the same time
Communication data traffic also can rapid growth, and optic communication is as the main flow of transmission network, the important component of access network, its capacity
Demand will constantly lift development.Moreover, Global Internet number of users is skyrocketed through.Under such a overall situation,
ITU-T(International Telecommunication Union Telecommunication Standardization
Sector, ITU Telecommunication Standardization Sector) tissue and IEEE (Institute of Electrical and
Electronics Engineers, IEEE) tissue all started the standard of respective New Generation Optical access network
Discuss.From 2012, ITU-T tissues and FSAN (Full Service Access Networks, FSAN opinion
Altar) tissue proceeds by NG PON2 (Next Generation Passive Optical Network2, next-generation passive light
Network) correlative study and standard formulation, and IEEE tissue to NG-EPON (Next Generation Ethernet
Passive Optical Network, Ethernet passive optical network of future generation) discussion also have begun to.
2012, FSAN was organized TWDM-PON (Time and Wavelength Division Multiplexing
PON, time-division Wave division multiplexing passive optical network) system elects NG-PON2 preferred scheme as.On the one hand, the system is based on wavelength heap
Folded scheme, technology relative maturity；On the other hand, the system still continues to use the Optical Distribution Network based on the unrelated optical branching device of wavelength, branch
Hold backward compatibility.Based on above-mentioned advantage, there is also preferable application prospect in TWDM-PON structure for the system.
How to realize inexpensive High Speed Modulation is the significant challenge during TWDM-PON is realized.The 100G of four wave stacks
TWDM-PON requires that Single wavelength speed is up to 25Gb/s, and currently used commercial devices bandwidth is in 10GHz or so.How with low
It is to need that cost device and simple technology, which realize Single wavelength 25Gb/s and the above modulation and support that more than 40km optical fiber transmits,
The problem of wanting emphasis to consider, the research for this problem mainly includes following two aspects：
On the one hand：It is related to device preparation, realizes High Speed Modulation with receiving by high-speed modulator and broadband receiver；Report
Road, which has, utilizes the directly modulated lasers for supporting 20Gb/s modulation rates that low cost is realized based on mixing silicon, III/V races material；Together
When how to improve receiver bandwidth and be also widely studied.
On the other hand：The bandwidth requirement to transmitting and receiver is reduced using high order modulation pattern.There is part at present
Related work is delivered.Find that 2014, Huawei Tech Co., Ltd was in fiber optic communication meeting (Optical Fiber through retrieval
Communication Conference) on delivered it is entitled " 30km Downstream Transmission Using 4 ×
25Gb/s 4-PAM Modulation with Commercial 10Gbps TOSA and ROSA for 100Gb/s-PON”
The article of (30 km transmissions of 4 × 25Gb/s 4-PAM signals based on commercial 10Gb/s transceiving devices).Described in this article
Following scheme：4-PAM (4 Pulse Amplitude Modulation, four level arteries and veins are realized using commercial 10Gbps devices
Rush amplitude modulation(PAM)) modulation and demodulation of the Single wavelength 25Gb/s signals of form.4-PAM modulation formats are a kind of Multilevel modulations,
Four kinds of impulse amplitudes can represent two bits, the baud rate of signal is reduced to the half of binary format, so as to drop
The low bandwidth demand to transceiver.The major defect of scheme in this article is：Dispersion is not accounted in area of light, so causing
Follow-up DSP (Digital Signal Processing, Digital Signal Processing) processing is relative complex, and system effect is also not very managed
Think.
In addition to 4-PAM, duobinary modulation is also a kind of conventional modulation system.Duobinary code belongs to a kind of related volume
Code technology, using the correlation between bit, switchs to three level by the electric signal of two level.Correlative coding is generally real by two ways
It is existing：1-bit delays are added or analogue low pass filtering.Low pass filter generally selects Bessel type, and three dB bandwidth is about signal bandwidth
1/4.Therefore, the spectrum efficiency of duobinary code improves nearly four times than two level, the duobinary system resisting chromatic dispersion ability of same rate
It is stronger.
Found through retrieval, the European optical-fibre communications exhibition in 2014 such as D.Van Veen of Alcatel-Lucent company
Entitled " 26-Gbps PON have been delivered in meeting (European Conference on Optical Communication)
Transmission over 40-km using Duo-binary Detection with a Low Cost 7-GHz APD-
Based Receiver " (the 40km transmission for the 26-Gb/s duobinary signals realized using 7GHz APD receivers) article,
Following scheme is proposed in this article：In ONU end, using the receiver of 7GHz bandwidth, realize that the duobinary system of 26Gb/s signals connects
Receive, be demodulated subsequently through duobinary system to binary demodulation circuit.The major defect of the program is：Connect although reducing
The bandwidth of receipts machine, but transmitting terminal stills need wideband modulator；And signal wavelength, in O wave bands, the wave band abbe number is very low, because
This program does not account for chromatic dispersion problem.
2015, D.Van Veen etc. IEEE Journal of Lightwave Technology (《Lightwave technology is miscellaneous
Will》) on delivered the entitled " dB of Demonstration of 40-Gb/s TDM-PON Over 42-km With 31 of an another piece
(the 31-dB power based on APD receivers is pre- by Optical Power Budget Using an APD-Based Receiver "
Calculate and the 40Gb/s time-division multiplex passive optical network systems demonstration of 42km optical fiber transmission) article, propose with lower section in this article
Case：Using narrow band modulator, realize that high speed Duo-binary (duobinary system pattern) is modulated, transmitting terminal by low pass filter,
OOK (On-Off Keying, on-off keying) is converted into Duo-binary patterns.But the receiving terminal in the program stills need
Broadband receiver.This article demonstrates 40-Gb/s signals and transmitted in the optical fiber of the 26km difference distances of C-band.Although employ
The less external modulation mode of chirp coefficient, still, for different transmission ranges, it is necessary to compensate different dispersion measures, specifically
Implementation process is very complicated.
Under conditions of low complex degree, realize that the modulated in real time of high speed signal and demodulation are that light of future generation connects with low speed devices
Urgent problem to be solved in networking.Or existing scheme realizes high-speed transfer using high speed device, system cost is very high；It is big
The dependence Digital Signal Processing of amount, the complexity of follow-up data processing is sharply increased, the real-time fortune of system can not be realized substantially
OK.
The content of the invention
The invention aims to overcome the shortcomings of above-mentioned background technology, there is provided one kind is realized at a high speed with low speed optical device
OLT in the symmetrical TWDM-PON systems of transmission, the cost of system can be significantly reduced, effectively reduce the complexity of system, drop
The difficulty of low system high-speed real-time transmission data.
The present invention provides the OLT in a kind of symmetrical TWDM-PON systems that high-speed transfer is realized with low speed optical device, should
TWDM-PON systems include optical line terminal OLT, branched system optical fiber, light distant-end node, some distribution type fiber-optics and some light nets
Network unit ONU, light distant-end node is between OLT and ONU, and one end of light distant-end node connects OLT by branched system optical fiber, separately
One end connects some ONU by some distribution type fiber-optics, and distribution type fiber-optic corresponds with ONU, it is characterised in that：The OLT
Including the first media control module, downlink data transmitter module, the first light wavelength division multiplexing and upstream data receiving module,
The up, descending of OLT shares the first light wavelength division multiplexing, the first media control module；Down direction, the first media
Control module, downlink data transmitter module, the first light wavelength division multiplexing are sequentially connected with；Up direction, the first light wavelength division multiplexing,
Upstream data receiving module, the first media control module are sequentially connected with；
Downlink data transmitter module includes multiple directly modulated lasers, the second light wavelength division multiplexing, an a cycle light
Wave filter and first image intensifer, one end of all directly modulated lasers is connected with the first media control module, another
End is connected with the second light wavelength division multiplexing, the second light wavelength division multiplexing, periodicity optical filter, the first image intensifer, the first light
Wavelength division multiplexer is sequentially connected；
Upstream data receiving module includes second image intensifer, a dispersion compensator with fixed dispersion measure
Part, a light Wave decomposing multiplexer and multiple row photodetectors, the quantity of row photodetectors and directly modulated lasers
Quantity is identical, and the first light wavelength division multiplexing, the second image intensifer, the dispersion compensation device with fixed dispersion measure, light wave decompose
Multiplexer is sequentially connected, and one end of all row photodetectors is connected with light Wave decomposing multiplexer, the other end and the first media
Medium control module is connected.
On the basis of above-mentioned technical proposal, the first media control module control in down direction, OLT is descending
The generation and processing of signal, downstream signal is modulated to caused by all directly modulated lasers on light carrier；Each directly modulated lasers production
Third contact of a total solar or lunar eclipse carrier wave, while corresponding electric signal is modulated on the light carrier, form downstream signal and send；Second light wavelength division multiplexing
The downstream signal sent to all directly modulated lasers carries out multiplexing process, and the downstream signal after multiplexing is issued into the filtering of periodicity light
Device；Periodicity optical filter is filtered to the downstream signal after multiplexing, realizes the frequency equilibrium and chirp management of downstream signal,
Filtered downstream signal is sent to the first image intensifer；First image intensifer is amplified to filtered downstream signal,
Downstream signal after amplification is sent to the first light wavelength division multiplexing；First light wavelength division multiplexing amplifies the first image intensifer
Downstream signal is transferred to light distant-end node by branched system optical fiber, and light distant-end node is transmitted downstream signal by distribution type fiber-optic
To each ONU.
On the basis of above-mentioned technical proposal, the first light wavelength division multiplexing in up direction, OLT passes upward signal
It is defeated to the second image intensifer；Second image intensifer amplifies upward signal；Dispersion compensation device with fixed dispersion measure is to up
Signal carries out dispersion compensation, and dispersion measure corresponding to all up channels is consistent；Light Wave decomposing multiplexer enters to upward signal
Row demultiplexing, by the uplink signal transmissions of different wave length to corresponding row photodetectors；Row photodetectors will be up
Optical signal is changed into electric signal, then by the electric signal transmission to the first media control module；First media controls mould
Block receives the electric signal that row photodetectors are sent, and the electric signal of reception is carried out at the conversion of four level to two level
Reason.
On the basis of above-mentioned technical proposal, different downlink data transmitter modules has different transmittings in the OLT
Wavelength, the wavelength interval between different downlink data transmitter modules meet ITU-T standard；Between wavelength between down channel
The integral multiple of the free spectrum intervals of periodicity optical filter is divided into, i.e. downstream signal spectrum is located at periodicity optical filter spectral pattern
Same position at：Rising edge or trailing edge；The free spectrum intervals of periodicity optical filter is tunable.
On the basis of above-mentioned technical proposal, all row photodetectors are the common photodetector of low speed.
On the basis of above-mentioned technical proposal, the directly modulated lasers have tunable wave length characteristic, its tunable wave length
Characteristic passes through temperature or current control.
On the basis of above-mentioned technical proposal, the dispersion compensation device with fixed dispersion measure include chirp grating,
Fiber Bragg Grating FBG, dispersion compensating fiber.
On the basis of above-mentioned technical proposal, the band of the directly modulated lasers in the downlink data transmitter module is a width of
10GHz。
On the basis of above-mentioned technical proposal, the row photodetectors in the upstream data receiving module use PIN
Type photodetector, four level signals are changed into two level signals with a width of 10GHz, and by simple decision circuit, it is real
The real-time processing of existing upstream data.
The dispersion compensation device on the basis of above-mentioned technical proposal, in the OLT with fixed dispersion measure is used for：Compensation
The up level pulse am signals of 25Gbps tetra-, its group delay is periodically variable with wavelength change；The dispersion compensation
The dispersion measure of device is -650ps/nm.
On the basis of above-mentioned technical proposal, the OLT realizes 0~40km of signal transmission distance seamless coverage.
Compared with prior art, advantages of the present invention is as follows：
(1) it is inexpensive：The present invention realizes the frequency equilibrium to downstream signal using the filter action of single optical filter
(Frequency Equalization) and chirp management (Chirp Management)；The dispersion fixed using single dispersion measure
Compensating device, the dispersion compensation to transmitting different distance upward signal is realized, the cost of system can be significantly reduced.
(2) it is backward compatible：The present invention has good backward compatibility in occasions such as access network, short distance interconnections, in tradition
10Gb/s systems on, without changing the framework of existing system, can be achieved with 25Gb/s High Speed Modulation, realize smooth liter
Level.
(3) high speed real-time Transmission：The present invention is descending to be examined using straight straightening, and upward signal transmitting is received using directly modulating
Only use four level and turn two level logic circuits in end, it is not necessary to extra Digital Signal Processing, can effectively reduce answering for system
Miscellaneous degree, reduce the difficulty of system high-speed real-time transmission data.
(4) present invention combines single optical filter and optical signal high order modulation realizes backward compatible symmetrical TWDM-PON systems
System, arrowband directly modulated lasers and narrow-band reception device can be utilized to realize High Speed Modulation and demodulation based on binary system pattern, it is real
The downlink transfer of existing signal；Optical dispersion compensation device can be reasonably used, with reference to high order modulation, realizes the up biography of signal
It is defeated, system cost is greatly reduced, promotes symmetrical TWDM-PON development.
(5) at up aspect, existing a large amount of dependence data signal processed offline technologies are different from, the present invention is in receiving terminal
By dispersion compensation device, light Wave decomposing multiplexer and multiple row photodetectors with fixed dispersion measure, realize up
Multiple wavelength, the high quality of different transmission ranges receive, the real-time reception of four level pulse amplitude modulation(PAM) (4-PAM) signals.
(6) at descending aspect, existing high order modulation technique is different from, employing binary system in the present invention is adjusted to form,
The receiving circuit using complexity in optical network unit is avoided, the reception cost of user terminal can be reduced.
(7) present invention can realize that the C-band of the symmetrical 4*25Gbps rate signals based on 10GHz narrowband devices is low sensitive
Degree damage 40km optical fiber transmission.
Brief description of the drawings
Fig. 1 is that the structure for realizing the symmetrical TWDM-PON systems of high-speed transfer with low speed optical device in the embodiment of the present invention is shown
It is intended to.
Fig. 2 is the group delay and wavelength graph of the dispersion compensation device with fixed dispersion measure.
Fig. 3 is dispersion compensation device of the addition with fixed dispersion measure, the eye pattern under back-to-back situation in up-link.
Fig. 4 is dispersion compensation device of the addition with fixed dispersion measure, the eye in the case where transmitting 20km situations in up-link
Figure.
Fig. 5 is dispersion compensation device of the addition with fixed dispersion measure, the eye in the case where transmitting 40km situations in up-link
Figure.
Fig. 6 is that the dispersion compensation device with fixed dispersion measure, the eye in the case where transmitting 20km situations are not added with up-link
Figure.
Fig. 7 is periodicity optical filter free transmission range, primary signal and the filtered flashlight spectrogram of filtered device.
Fig. 8 is eye pattern of the signal under back-to-back situation in downlink after filtering.
Fig. 9 is eye pattern of the signal after 40km optical fiber is transmitted in downlink after filtering.
Figure 10 is eye pattern of the signal not filtered in downlink after 40km optical fiber is transmitted.
Embodiment
Below in conjunction with the accompanying drawings and specific embodiment the present invention is described in further detail.
Shown in Figure 1, the embodiment of the present invention provides a kind of symmetrical TWDM- that high-speed transfer is realized with low speed optical device
OLT in PON system, the TWDM-PON systems include OLT (Optical Line Terminal, optical line terminal), branched system
Optical fiber, light distant-end node, some distribution type fiber-optics and some ONU (Optical Network Unit, optical network unit), light is remote
End node is between OLT and ONU, and one end of light distant-end node connects OLT by branched system optical fiber, and the other end passes through some points
Cloth optical fiber connects some ONU, and distribution type fiber-optic corresponds with ONU.
OLT includes the first media control module, downlink data transmitter module, the first light wavelength division multiplexing and upper line number
According to receiving module, the up, descending of OLT shares the first light wavelength division multiplexing, the first media control module；Down direction,
First media control module, downlink data transmitter module, the first light wavelength division multiplexing are sequentially connected with；Up direction, first
Light wavelength division multiplexing, upstream data receiving module, the first media control module are sequentially connected with.Downlink data transmitter module bag
Include multiple directly modulated lasers, second light wavelength division multiplexing, a cycle optical filter and first image intensifer, institute
The one end for having directly modulated lasers is connected with the first media control module, and the other end is connected with the second light wavelength division multiplexing, the
Two light wavelength division multiplexings, periodicity optical filter, the first image intensifer, the first light wavelength division multiplexing are sequentially connected.Upstream data
Receiving module includes second image intensifer, a dispersion compensation device with fixed dispersion measure, a light wave and decomposed again
With device and multiple row photodetectors, the quantity of row photodetectors is identical with the quantity of directly modulated lasers, the first light wave
Division multiplexer, the second image intensifer, the dispersion compensation device with fixed dispersion measure, light Wave decomposing multiplexer are sequentially connected, institute
The one end for having row photodetectors is connected with light Wave decomposing multiplexer, and the other end is connected with the first media control module.
Each ONU include the 3rd light wavelength division multiplexing, downlink data receiving module, the second media control module and
Upstream data transmitter module, ONU up, descending shared 3rd light wavelength division multiplexing, the second media control module are descending
Direction, the 3rd light wavelength division multiplexing, downlink data receiving module, the second media control module are sequentially connected with；Up direction,
Second media control module, upstream data transmitter module, the 3rd light wavelength division multiplexing are sequentially connected with.Upstream data launches mould
Block includes low speed EML (Eroabsorption Modulated Laser, Electroabsorption Modulated Laser), and low speed EML has ripple
Long tunable characteristic, the upward signal for being sent to the second media control module carry out four level pulse amplitude modulation(PAM)s
(4-PAM).Downlink data receiving module includes tunable optical filter, row photodetectors, the 3rd light wavelength division multiplexing, adjustable
Optical filter, row photodetectors, the second media control module are sequentially connected.
Down direction：The generation and processing of the first media control module control downstream signal in OLT, by descending letter
Number it is modulated to caused by all directly modulated lasers on light carrier；Each directly modulated lasers produce light carrier, while by corresponding telecommunications
Number it is modulated on the light carrier, forms downstream signal；The descending letter that second light wavelength division multiplexing is sent to all directly modulated lasers
Number carry out multiplexing process, the downstream signal after multiplexing is issued into periodicity optical filter；After periodicity optical filter is to multiplexing
Downstream signal is filtered, and realizes the frequency equilibrium and chirp management of downstream signal, that is, the effect filtered includes two aspects：Frequently
Rate equilibrium and chirp management；Filtered downstream signal is sent to the first image intensifer；First image intensifer is to filtered
Downstream signal is amplified, and the downstream signal after amplification is sent into the first light wavelength division multiplexing；First light wavelength division multiplexing will
The downstream signal of first image intensifer amplification is transferred to light distant-end node by branched system optical fiber, and light distant-end node passes through distribution
Downstream signal is transferred to each ONU by optical fiber；Downstream signal is transferred to downlink data and connect by the 3rd light wavelength division multiplexing in each ONU
Receive module；Tunable optical filter in downlink data receiving module is filtered to downstream signal, obtains the optical signal of Single wavelength；
The optical signal of Single wavelength is changed into electric signal by row photodetectors, is transferred to the second media control module, the second matchmaker
Body medium control module is transferred to customer side after handling the electric signal of reception；Second media control module always according to
Control protocol, controls the reception of downstream signal, the centre wavelength of major control tunable optical filter and downstream signal reception when
Gap.
Up direction：The second media control module in each ONU controls the production of upward signal according to control protocol
The raw, launch wavelength of upstream data transmitter module and the time slot of transmission, caused uplink signal transmissions to upstream data are launched
The upward signal that low speed EML in module, low speed EML are sent to the second media control module carries out four level pulse amplitudes
Modulate (4-PAM), the uplink signal transmissions of four level pulse amplitude modulation(PAM)s (4-PAM) will be passed through to the 3rd light wavelength division multiplexing；
3rd light wavelength division multiplexing will be arrived by distribution type fiber-optic by the uplink signal transmissions of four level pulse amplitude modulation(PAM)s (4-PAM)
Light distant-end node, the wavelength of the upward signal in different ONU can be tuned as needed, and operation wavelength may be the same or different；
Light distant-end node couples to the upward signal of each ONU different wave lengths transmitted, then by branched system optical fiber by after coupling
Uplink signal transmissions are to OLT；The first light wavelength division multiplexing in OLT is by uplink signal transmissions to the second image intensifer；Second light
Amplifier amplifies upward signal；Dispersion compensation device with fixed dispersion measure carries out dispersion compensation to upward signal, for reality
Handled while existing multi-wavelength signals, dispersion measure should be consistent corresponding to all up channels；Light Wave decomposing multiplexer is to upper
Row signal is demultiplexed, by the uplink signal transmissions of different wave length to corresponding row photodetectors；Up photodetection
Uplink optical signal is changed into electric signal by device, then by the electric signal transmission to the first media control module；First media are situated between
Matter control module receives the electric signal that row photodetectors are sent, and carries out four level to two level to the electric signal of reception
Conversion process.
Dispersion compensation device with fixed dispersion measure is the dispersion compensation device that a kind of dispersion measure is fixed, such as：Chirp
Grating, FBG (Fiber Bragg Grating, Fiber Bragg Grating FBG), DCF (dispersion compensation
Fiber, dispersion compensating fiber) etc..
Directly modulated lasers have tunable wave length characteristic, its tunable wave length characteristic can by temperature or current control,
It is to change the chamber length of laser to change the most basic method of wavelength, is exactly by expanding with heat and contract with cold or electroluminescent refraction index changing swashs herein
The chamber length of light device.
Different downlink data transmitter modules has different launch wavelengths, different downlink data transmitter modules in OLT
Between wavelength interval meet ITU-T standard, such as：Wavelength interval is arranged to 100GHz.In order to realize multi-wavelength signals
Handle simultaneously, the wavelength interval between down channel should be the integral multiple of the free spectrum intervals of periodicity optical filter, be
Realize that multi-wavelength signals are handled simultaneously, downstream signal spectrum be located at the same position of periodicity optical filter spectral pattern (rising
Edge or trailing edge)；The free spectrum intervals of periodicity optical filter is tunable.
All row photodetectors, row photodetectors are the common photodetector of low speed.
Light distant-end node can be 1 by splitting ratio：N optical branching/combiner (Splitter) composition, N take 64,128 or
256。
The present invention core concept be：Descending, using optical filter technology to the high speed signal that is modulated on narrowband device
Frequency equilibrium and chirp management are carried out, it is achieved thereby that based on 10GHz arrowbands directly modulated lasers and 10GHz narrow-band receivers
The direct modulation of 25Gbps OOK (On-Off Keying, on-off keying) signal, directly detection and 40km downlink transfer；
Up, the characteristics of using high order modulation high spectrum utilization and signal chirp, realization is swashed based on 10GHz arrowbands electro-absorption modulation
The direct modulation of 25Gbps 4-PAM signals and 40km uplink of light device (EML) and 10GHz narrow-band receivers.
Below by entering exemplified by a symmetrical TWDM-PON system of low cost based on 10GHz optical devices transmission high speed signal
Row describes in detail.
The up-downgoing Single wavelength transmission rate of the system is 25Gbps, and four wavelength simultaneous transmissions realize symmetrical TWDM-PON
System, it is shown in Figure 1, the TWDM-PON systems include OLT, branched system optical fiber, light distant-end node, some distribution type fiber-optics and
Some ONU, wherein, one end of branched system optical fiber is connected with OLT, the other end connection light distant-end node of branched system optical fiber, distribution
The both ends of formula optical fiber connect light distant-end node and ONU respectively, and light distant-end node is that splitting ratio is 1：N optical branching/combiner, N
64,128 or 256 are taken, its occurrence needs to consider the optical power budget of the transmission distance discrete system in system.Optical branching/
Combiner (Splitter) by distribution type fiber-optic connect ONU1, ONU2, ONU3 ..., ONU N.
There are 4 directly modulated lasers, 4 row photodetectors in Fig. 1, it can realize inexpensive, high performance symmetrical 4 ×
25G TWDM-PON systems；Similarly, when directly modulated lasers, row photodetectors are 2, low cost, height can be realized
Symmetrical 2 × 25G of performance TWDM-PON systems；When directly modulated lasers, row photodetectors are 10, can realize
Inexpensive, high performance symmetrical 10 × 25G TWDM-PON systems.
The descending output port of 4 directly modulated lasers is all connected to the descending input port of the second light wavelength division multiplexing, the
The descending output port of two light wavelength division multiplexings is connected to the descending input port of periodicity optical filter, periodicity optical filter
Descending output port be connected to the descending input port of the first image intensifer, the descending output port of the first light wavelength division multiplexing
It is coupled in branched system optical fiber.
The a width of 10GHz of band of directly modulated lasers in downlink data transmitter module；It is up in upstream data receiving module
Photodetector uses PIN (Positive Intrinsic Negative Diode, photodiode) type photodetection
Device, four level signals are changed into two level signals with a width of 10GHz, and by simple decision circuit, realize upstream data
Processing in real time.
The dispersion compensation device in OLT with fixed dispersion measure is used for：The up level pulse amplitudes of 25Gbps tetra- are compensated to adjust
Signal processed, its group delay are shown in Figure 2 with wavelength curve, it can be seen that its group delay is cyclically-varying with wavelength change
's.Because group delay is exactly the dispersion measure of signal to wavelength derivation, figure it is seen that the dispersion measure of the dispersion compensation device
About -650ps/nm.Fig. 3, Fig. 4, Fig. 5 are to add the dispersion compensation device in receiving terminal respectively, back-to-back, transmission 20km,
Transmit the eye pattern under 40km situations, it can be seen that three eye patterns are four level eye-diagrams of opening, so as to illustrate that the program can be with
Realize 0~40km of signal transmission distance seamless coverage.The dispersion compensation device with fixed dispersion measure is not added with up-link,
Eye pattern in the case where transmitting 20km situations is shown in Figure 6.Four level conversions are only two electricity in receiving terminal by the embodiment of the present invention
Flat can completes demodulation, it is not necessary to adds the DSP algorithms such as other dispersion compensations, greatly reduces the complexity of demodulation.
OLT periodicity optical filter is used for the frequency equilibrium and chirp management for simultaneously carrying out downstream signal.By reality
The feasibility of the program is verified, the spectral type curve of its periodicity optical filter is shown in Figure 2, periodicity optical filter passband model
Enclose, primary signal and the filtered flashlight spectrogram of filtered device it is shown in Figure 7, the signal in downlink after filtering
Eye pattern under back-to-back situation is shown in Figure 8, eye of the signal in downlink after filtering after 40km optical fiber is transmitted
Scheme shown in Figure 9, eye pattern of the not filtered signal after 40km optical fiber is transmitted is shown in Figure 10 in downlink, it is seen that
One device of periodicity optical filter can realize frequency equilibrium and dispersion management simultaneously, realize 0~40km seamless high quality,
Low cost signal transmits.Simultaneously because the periodic filtering characteristic of wave filter, can realize the management to multiple wavelength simultaneously.
In ONU, a width of 10GHz of band of downlink data receiving module；Upstream data transmitter module has at least 10Gb/s numbers
According to modulation capability, while there is tunable wave length function, to realize that ONU's is decolorizable, according to being actually needed, by different ONU
Data be modulated to required for wavelength on.
The present embodiment realizes the symmetrical 4 × 25G-PON of up-downgoing speed, the party using the 10GHz optical devices of low cost
Case has advantages below：
(1) using the dispersion compensation device with fixed dispersion measure, the dispersion compensation of upward signal multi-wavelength is realized, is realized
The full light processing of dispersion compensation, greatly reduces system complexity, improves the ageing of system.
(2) a cycle optical filter is utilized, downstream signal multi-wavelength frequency equilibrium and dispersion management is realized, realizes
All-optical signal processing, avoid the use of high speed electrical dispersion compensation module and electric frequency equalizing algorithm.
(3) periodicity device is easily integrated realization, can be integrated together with OLT other devices, largely
Reduce the size of device, reduce system cost.
(4) 4 × 25G-PON systems do not change the knot of the optical fiber distributed type network of the existing PON system laid
Structure, but also the light distant-end node structure in existing PON system can be continued to use, thus can be carried out in existing PON system smooth
Upgrading, and it is completely compatible with existing PON system, and then the upgrade cost of PON system can be reduced to a certain extent.
Those skilled in the art can carry out various modifications and variations to the embodiment of the present invention, if these modifications and change
Type is within the scope of the claims in the present invention and its equivalent technologies, then these modifications and variations are also in protection scope of the present invention
Within.
The prior art that the content not being described in detail in specification is known to the skilled person.
Claims (11)
1. the OLT in a kind of symmetrical TWDM-PON systems that high-speed transfer is realized with low speed optical device, the TWDM-PON system bags
It is remote to include optical line terminal OLT, branched system optical fiber, light distant-end node, some distribution type fiber-optics and some optical network unit ONUs, light
End node is between OLT and ONU, and one end of light distant-end node connects OLT by branched system optical fiber, and the other end passes through some points
Cloth optical fiber connects some ONU, and distribution type fiber-optic corresponds with ONU, it is characterised in that：The OLT is situated between including the first media
Matter control module, downlink data transmitter module, the first light wavelength division multiplexing and upstream data receiving module, OLT's is up, descending
Share the first light wavelength division multiplexing, the first media control module；Down direction, it is the first media control module, descending
Data transmission module, the first light wavelength division multiplexing are sequentially connected with；Up direction, the first light wavelength division multiplexing, upstream data receive
Module, the first media control module are sequentially connected with；
Downlink data transmitter module includes multiple directly modulated lasers, second light wavelength division multiplexing, the filtering of a cycle light
Device and first image intensifer, one end of all directly modulated lasers are connected with the first media control module, the other end with
Second light wavelength division multiplexing is connected, the second light wavelength division multiplexing, periodicity optical filter, the first image intensifer, the first light wave point
Multiplexer is sequentially connected, and the periodicity optical filter is used to realize frequency equilibrium and dispersion management；
Upstream data receiving module includes second image intensifer, the dispersion compensation device with fixed dispersion measure, one
Individual light Wave decomposing multiplexer and multiple row photodetectors, the quantity of row photodetectors and the quantity phase of directly modulated lasers
Together, the first light wavelength division multiplexing, the second image intensifer, the dispersion compensation device with fixed dispersion measure, light Wave decomposing multiplexer
It is sequentially connected, one end of all row photodetectors is connected with light Wave decomposing multiplexer, the other end and the first media control
Molding block is connected, and the first media control module is used for the conversion that four level to two level are carried out to the electric signal of receiving
Processing.
2. realizing the OLT in the symmetrical TWDM-PON systems of high-speed transfer with low speed optical device as claimed in claim 1, it is special
Sign is：The generation and processing of the first media control module control downstream signal in down direction, OLT, will be descending
Caused by signal modulation to all directly modulated lasers on light carrier；Each directly modulated lasers produce light carrier, while will corresponding electricity
Signal modulation is sent on the light carrier, forming downstream signal；Second light wavelength division multiplexing is sent to all directly modulated lasers
Downstream signal carries out multiplexing process, and the downstream signal after multiplexing is issued into periodicity optical filter；Periodicity optical filter is to multiple
Downstream signal after is filtered, and realizes the frequency equilibrium and chirp management of downstream signal, filtered downstream signal is sent out
It is sent to the first image intensifer；First image intensifer is amplified to filtered downstream signal, and the downstream signal after amplification is sent out
It is sent to the first light wavelength division multiplexing；The downstream signal that first image intensifer amplifies is passed through branched system light by the first light wavelength division multiplexing
Fibre is transferred to light distant-end node, and downstream signal is transferred to each ONU by light distant-end node by distribution type fiber-optic.
3. realizing the OLT in the symmetrical TWDM-PON systems of high-speed transfer with low speed optical device as claimed in claim 1, it is special
Sign is：The first light wavelength division multiplexing in up direction, OLT is by uplink signal transmissions to the second image intensifer；Second light
Amplifier amplifies upward signal；Dispersion compensation device with fixed dispersion measure carries out dispersion compensation, Suo Youshang to upward signal
Dispersion measure corresponding to row channel is consistent；Light Wave decomposing multiplexer demultiplexes to upward signal, by the upper of different wave length
Row signal is transferred to corresponding row photodetectors；Uplink optical signal is changed into electric signal by row photodetectors, then will
The electric signal transmission is to the first media control module；First media control module receives row photodetectors and sent
Electric signal, and the conversion process of four level to two level is carried out to the electric signal of reception.
4. realizing the OLT in the symmetrical TWDM-PON systems of high-speed transfer with low speed optical device as claimed in claim 1, it is special
Sign is：Different downlink data transmitter modules has different launch wavelengths, different downlink datas transmitting mould in the OLT
Wavelength interval between block meets ITU-T standard；Wavelength interval between down channel is the freedom of periodicity optical filter
The integral multiple of spectrum intervals, i.e. downstream signal spectrum are located at the same position of periodicity optical filter spectral pattern：Rising edge or
Trailing edge；The free spectrum intervals of periodicity optical filter is tunable.
5. the symmetrical TWDM-PON systems that high-speed transfer is realized with low speed optical device as any one of claim 2 to 4
In OLT, it is characterised in that：All row photodetectors are the common photodetector of low speed.
6. the symmetrical TWDM-PON systems that high-speed transfer is realized with low speed optical device as any one of claim 2 to 4
In OLT, it is characterised in that：The directly modulated lasers have tunable wave length characteristic, and its tunable wave length characteristic passes through temperature
Or current control.
7. the symmetrical TWDM-PON systems that high-speed transfer is realized with low speed optical device as any one of claim 2 to 4
In OLT, it is characterised in that：The dispersion compensation device with fixed dispersion measure includes chirp grating, optical fiber Bragg light
Grid, dispersion compensating fiber.
8. the symmetrical TWDM-PON systems that high-speed transfer is realized with low speed optical device as any one of claim 2 to 4
In OLT, it is characterised in that：The a width of 10GHz of band of directly modulated lasers in the downlink data transmitter module.
9. realizing the OLT in the symmetrical TWDM-PON systems of high-speed transfer with low speed optical device as claimed in claim 8, it is special
Sign is：Row photodetectors in the upstream data receiving module use photodiode PIN type photodetectors,
Four level signals are changed into two level signals with a width of 10GHz, and by simple decision circuit, realize the real-time of upstream data
Processing.
10. the OLT in the symmetrical TWDM-PON systems of high-speed transfer is realized with low speed optical device as claimed in claim 8, its
It is characterised by：The dispersion compensation device in the OLT with fixed dispersion measure is used for：Compensate the up level pulse width of 25Gbps tetra-
Modulated signal is spent, its group delay is periodically variable with wavelength change；The dispersion measure of the dispersion compensation device is -650ps/
nm。
11. the OLT in the symmetrical TWDM-PON systems of high-speed transfer is realized with low speed optical device as claimed in claim 10, its
It is characterised by：The OLT realizes 0~40km of signal transmission distance seamless coverage.
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| CN107645337B (en) * | 2016-07-20 | 2020-05-05 | 上海诺基亚贝尔股份有限公司 | Method and apparatus for transmitting and receiving data |
| CN106411451A (en) * | 2016-07-27 | 2017-02-15 | 许继电气股份有限公司 | Method for realizing service isolation in power distribution network through adoption of TWDM-PON (Passive Optical Network) |
| CN106330319B (en) * | 2016-11-10 | 2019-06-07 | 成都必合科技有限公司 | A kind of local side apparatus and three-network integration system |
| CN113596634B (en) * | 2021-07-30 | 2023-09-26 | 武汉光迅科技股份有限公司 | Combo PON OLT monolithic integrated chip and optical component thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101399617A (en) * | 2007-09-25 | 2009-04-01 | 日立通讯技术株式会社 | Optical line terminating apparatus and optical communication system |
| CN101729949A (en) * | 2009-12-21 | 2010-06-09 | 烽火通信科技股份有限公司 | WDM PON device with dynamically allocable wavelengths |
| CN102318278A (en) * | 2009-02-10 | 2012-01-11 | 三菱电机株式会社 | Parent station device and grant allocation method |
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|---|---|---|---|---|
| CN101399617A (en) * | 2007-09-25 | 2009-04-01 | 日立通讯技术株式会社 | Optical line terminating apparatus and optical communication system |
| CN102318278A (en) * | 2009-02-10 | 2012-01-11 | 三菱电机株式会社 | Parent station device and grant allocation method |
| CN101729949A (en) * | 2009-12-21 | 2010-06-09 | 烽火通信科技股份有限公司 | WDM PON device with dynamically allocable wavelengths |
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