TWDM

[Rajguru M. Mohan]

Hi everyone,
On April 2012,after the meeting of the Full Service Access Network (FSAN) group,
time and wavelength division multiplexed passive optical network (TWDM-PON) technology
was chosen as the primary solution for next-generation passive optical network stage-2 (NG-PON2) architecture,
the evolving specifications are wavelength plans, loss budgets, and key technologies that enable tunable ONUs.

So, i want to work on time and wavelength division multiplexed PON.
I have tried to design TWDM-PON in optisystem , but didn’t get results.
I request you all to please , if possible to Upload the osd file of TWDM-PON.
So, that i could enhance the system.
You could even share some important links related to it.

Seeking your response.

[Rajguru M. Mohan]

Hi,
I know some of basic parameters, technologies and requirements related to it like:
Tunable transmitters comprises of
Distributed feedback (DFB) laser with temperature control (TC),
External cavity laser (ECL) with mechanical control without cooling,
Tunable receivers with following :Liquid-crystal tunable filter,
Thermally-tuned Fabry-Perot (FP) filter
The prototype of TWDM employs the C-band wavelength plan to achieve coexistence
with the previous generations of PON, while the four downstream wavelengths are spaced 200GHz apart.

So, please share some advanced and necessary elements related to it.
Thanks and Regards,
Rajguru

[FAYIQA NAQSHBANDI]

Hi RAJGURU..

Thank you for sharing this piece..It might be very useful.

Regards
FAYIQA

[nagesh kuknoor]

Hi ranjeet,
Thank you for sharing such information. Well i have heard of tunable lasers for improving system performance. And also about the externally modulated lasers for the same thing. What actually you want to implement?

Regards

[Ankita Sharma]

Hi Rajguru,

Thanks for sharing information… I agree here with Nagesh, about tunable lasers for improving system performance..

Regards

[Rajguru M. Mohan]

Hi Nagesh,
As i have discussed that i want to basic TWDM system like 4 users.
I have asked for osd file of TWDM system.
If possible, at least share instructions to design TWDM system properly, this may be in the form of image or pdf or links.

If you know how to implement tunable lasers for improving system performance and externally modulated lasers in optisystem.
Also share this.
Regards,
Rajguru.

[Rajguru M. Mohan]

Hi ankita,
Please suggest some links or instructions for implememtation TWDM system.

Regards,
Rajguru

[Rahul Tiwari]

Hi Rajguru,

I also agree with Nagesh about The fact that tunable lasers improve system performance..

Regards
Rahul Tiwari

[Kanwarjeet Singh]

Hello Rajguru,
I want to know if thermally tuned fabry parot lasers are available in optisystem. I would appreciate your response. Thanking you.

Regards
Kanwarjeet

[FAYIQA NAQSHBANDI]

HELLO KANWARJEET..

As far as i know there are no such filters in Optisystem . hope it helps.

Regards
Fayiqa

[Kanwarjeet Singh]

Hi Dear,
Thank you for it. I thought Mr. Rajguru has shared it with that purpose only. Anyway Thank you.

Regards

[FAYIQA NAQSHBANDI]

You are welcome anytime.

[Kanwarjeet Singh]

Thanks Dear for the gratitude.

Regards
Kanwarjeet

[FAYIQA NAQSHBANDI]

Cheers..

[Rahul Tiwari]

Hi all,

Which filters are not there ?

Regards
Rahul Tiwari

[Rajguru M. Mohan]

Hi kanwarjeet,
I think we don’t have thermally tuned fabry parot lasers in optisystem tiil date.
Hope it would be added in component library soon.

Thanks

[Rajguru M. Mohan]

Hi Ankita,
We have lots of benefits of tunable laser. They are as:
As tunable lasers are classified into three structural types: an external cavity laser,
a distributed feedback (DFB) laser array, and a distributed Bragg reflector (DBR) laser.
All of these laser structures provide a tuning range of more than 35 nm, which is required for DWDM systems.
Another important aspect of the tunable lasers
performance, when switching between wavelengths, is
the wavelength stability of the device. As the laser tunes
into its desired wavelength, there is a settling drift before
the channel finally stabilizes. This drift can have a large
impact on the performance of a dense wavelength
division multiplexed system (causing adjacent channel
interference) and therefore must be fully characterized, in
terms of both the magnitude of the drift and the time it
takes to settle to the destination wavelength.
The external cavity laser which can an easily provide a wide tuning range because optimum optical filters can be selected.
This laser is a strong light source for digital coherent systems.
Its drawbacks are that complex tuning control is needed to suppress mode hopping and that it has many optical parts.

Thanks

[FAYIQA NAQSHBANDI]

HELLO RAJGUR..

That is exactly what i had mentioned earlier..We have no of benefits by using tunable lasers at the receiver end..I hope it helps you.

Regards

[Rajguru M. Mohan]

Hi,
Now i am adding the benefits of 2nd type of tunable laser i.e. distributed feedback (DFB) laser array.
The DFB laser array is based on the DFB laser, which has been widely used in commercial optical networks for a long time.
The tuning range is expanded by integrating DFB lasers of different wavelengths.
An excellent feature of this laser is its mode stability and
reliability owing to its mode-hop-free tuning characteristics.
Moreover, it is suited to mass production because it is a monolithic chip.
Its drawback is its slow wavelength tuning, which is achieved through temperature control.
DFB array lasers are widely used in current 10-Gbit/s systems.
The linewidth of the conventional DFB laser is several megahertz.
However, a narrower linewidth can be obtained by optimizing the cavity structure.

Thanks

[Rajguru M. Mohan]

Hi,
And finally we have distributed Bragg reflector (DBR) laser.
A DBR laser is also a monolithic chip. The wavelength can be tuned by
controlling the refractive index of the semiconductor-based DBR.
Generally, the refractive index is changed by a carrier plasma effect induced by current injection.
Therefore, the tuning time is a short as a few nanoseconds.
Its drawback is that the linewidth is increased when the tuning current is injected.
However, it has been reported that a DBR-type laser with heaters for
temperature-based wavelength tuning has a narrow linewidth even during wavelength tuning.

The all benefits and some drawbacks of tunable lasers being discussed.

Thanks

[FAYIQA NAQSHBANDI]

HI RAJGURU..

Thank you for the valuable information..I appreciate that.

Regards

[Rajguru M. Mohan]

You are most welcome FAYIQA NAQSHBANDI.

[love kumar]

hi Rajguru … sending you a paper on TWDM 4 channel system ..i guess it will be beneficial to you..please find the attachment ….. if facing any problem in downloading .. send me a test mail on er.lovekumar@gmail.com

[love kumar]

another file

[Rajguru M. Mohan]

Hi Love kumar,
Thank you so much for such valuable information.
I have read both papers, both are useful and important specially the second one:
Time- and Wavelength-Division Multiplexed Passive Optical Network (TWDM-PON) for Next-Generation PON Stage 2 (NG-PON2) of
JOURNAL OF LIGHTWAVE TECHNOLOGY.
By reading this we get valuable information about time- and wavelength-division multiplexed passive
optical network (TWDM-PON), tunable receiver, tunable transmitter.

I want to share some important information about TWDM to all of you :
Among all of the proposals for different technologies of NGPON2, TWDM-PON
has attracted the majority support from global vendors and was
selected by the FSAN community in the April 2012 meeting as a
primary solution to NG-PON2. TWDM-PON increases the aggregate
PON rate by stacking XG-PONs via multiple pairs of
wavelengths. An XG-PON system offers the access rates of 10
Gb/s in downstream and 2.5 Gb/s in upstream. A TWDM-PON
system with four pairs of wavelengths is able to provide 40 Gb/s
and 10 Gb/s in downstream and upstream, respectively. Each
TWDM-PON ONU can provide peak rates up to 10 Gb/s downstream
and 2.5 Gb/s upstream. This meets the rate requirements
of NG-PON2.
Hence TWDM is most important technologies for NGPON2.

Thanks

[Karan Ahuja]

Hi Rajguru
As we know studies have been carried out on NG-PON2 enabling technologies, such as 40 G TDM-PON,wavelength division multiplexed PON (WDM-PON), time and wavelength division multiplexed PON (TWDM-PON) and orthogonal frequency division multiplexing PON(OFDM-PON).
And among all these technologies, TWDM-PON has beenselected as the best candidate for NG-PON2 because itsupports backward compatibility, flexibility and static sharing.
At the OLT side, a set of laser diodes such as distributedfeedback (DFB) laser diodes operating at different wave-lengths serve as downstream laser sources, followed by aWDM for multiplexing.
Therefore, ONU must contain tunable trans-mitters and receivers devices. A tunable filter at thereceiver is used to select or tune to any of the fourdownstream wavelengths. In case of upstream wave-lengths, the tunable laser is used to provide colorlessONU (free operation wavelength) to enable easier networklaying and maintenance.

Regards

[Hamza Ali Abbas Khan]

Hello Rajguru m Mohan,
I would like to mention that The main challenges of implementing NG-PON2 (TWDM PON) are the spectrum allocation and the need for “colourless” ONTs, which must be able to send and receive signals on any of the specified wavelengths. The ONT transmitter must be tunable while the receiver requires a tunable filter. Colourless ONTs based on tunable transmitters and receivers are likely to be more expensive than GPON ONTs. Optical component vendors are developing new technologies to help bring down costs. The use of photonic integrated circuits (PICs) in the ONT is highly attractive because a low-cost manufacturing process would enable mass deployment. Furthermore, since tuning technologies mainly rely on temperature control, a key challenge is to maintain low power consumption in the ONT.
Therefore, colourless” ONTs have importance with reference to selection of the the transceiver section of the Optical Line Terminal Units (OLT) and Optical Network Terminals (ONUs) in TWDM-PON.
Hope this is helpful.

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