BEST TRANSMITTER/RECIEVERs for TWDM-PON

[FAYIQA NAQSHBANDI]

Out of the available transmitters and receivers in the optiwave library.Which ones should I prefer for designing the transceiver section of the Optical Line Terminal Units (OLT) and Optical Network Terminals (ONUs) in TWDM-PON ?

[aasif bashir dar]

hi fayiqa,

actually i did not get your query correctly..

because we have the either PIN or APD as the reciever option ..

and as far as tranmitter is considered we have various option;
like DMLs
EMLs
with regards

[aasif bashir dar]

hi fayiqa,
DMLs called as directly modulated lasers… will provide you got results for very long link as compared to EMLs
EMLS called as externally modulated lasers.. will provide overall better quality for small links as compared to DMLs

you are taking about PON networks wich have ususlly small range

it is better to use EMLS

with regards

[FAYIQA NAQSHBANDI]

HI AASIF BASHIR..
Thanks u for your reply but the things you are mentioning i have already gone through those and these are theoretical perspectives… i wanted to know if someone has already designed any system and what trans-receiver sections one has used.. And as far as EMLs and DMLs are concerned there implementation is largely affected by their applications..
Thanks & regards

[Dr. Dhiman Kakati]

Hi FAYIQA NAQSHBANDI,
I think you should go for advanced modulation schemes because it has so many advantages such as high bit rate, more transmission distance, spectral efficiency. but all of them do not have all the three above mentioned quality. so it would be better you mention the specification you are going to achieve then your query will be more clearer. thanking you..

Regards,
Dhiman

[FAYIQA NAQSHBANDI]

HELLO DHIMAN..

Yes i agree to your point that its better to go for advanced modulation schemes.But the cost and complexity of such circuits is very high…I wish to achieve the same performance as provided by advanced schemes at much lower complexity and cost….Also my major focus is to achieve a high power budget for TWDM-PON Networks which can be achieved at high values of transmitter power.
And DMLs show an improved performance over externally modulated transmitters at very high levels of launch power…
Thanks & regards

[Dr. Dhiman Kakati]

Hi Fayiqa,
I think going towards high launch power or transmitter power is definitely help you in some aspects including as you have mentioned. but in most of the cases in our design in optisystem we have not considered the fiber nonlinearity but in practical systems it is mostly required to make the transmitter power low (in terms of power budget also). so you have take into consideration all the probable issues (such as temporal variation in the refractive index). Nonlinear effects in optical fibers occur due to (1) change in the refractive index of the medium with optical intensity and, (2) inelastic scattering phenomenon. Thanking you.

Regards,
Dhiman

[FAYIQA NAQSHBANDI]

HELLO DHIMAN..

You have correctly mentioned it we cannot increase the launching power or keep it very high.. it needs to be on optimum side and as per the ITU-T guidelines. However in some cases just like FSO the launching power needs to be on higher side as it has to transmit wirelessly..
and u are right Nonlinear effects in optical fibers occur due to change in the refractive index of the medium with optical intensity but i don’t have any idea how to simulate that change.. Anyways it was a healthy discussion.
Thanks & regards

[Ranjeet Kumar]

Hi Fayiqa ma’m
All the TWDM ONTs must be colorless. The ONT transceiver must be able to tune to the correct wavelengths in upstream and downstream during end-user provisioning.
We can use a variety of techniques to control the wavelength in the upstream direction from the ONT to the OLT. Temperature is the primary parameter of control. all TWDM ONTs must be colorless. The ONT transceiver must be able to tune to the correct wavelengths in upstream and downstream during end-user provisioning.

Operators can use a variety of techniques to control the wavelength in the upstream direction from the ONT to the OLT. Temperature is the primary parameter of control.
n the long-term, it is hoped that photonic integrated circuits will provide other economical solutions to wavelength control.

In the downstream direction, thermo-controlled thin-film filters can be integrated into the ONT receiver to allow tuning. Photonic integrated circuits may provide a future solution.

[FAYIQA NAQSHBANDI]

HELLO RANJEET..
Thanks for sharing many important points but here i would like to ask you in what context you mean that All the TWDM ONTs must be colorless..
Which does it imply..??
Does it have any 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..?
I would appreciate if you explain a little further on this..
Thanks & regards

[Ranjeet Kumar]

Hi FAYIQA NAQSHBANDI Ma’m
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.

[Manoj Kumar]

I think going towards high launch power or transmitter power is definitely help you in some aspects including as you have mentioned. but in most of the cases in our design in optisystem we have not considered the fiber nonlinearity but in practical systems it is mostly required to make the transmitter power low (in terms of power budget also). so you have take into consideration all the probable issues (such as temporal variation in the refractive index). Nonlinear effects in optical fibers occur due to (1) change in the refractive index of the medium with optical intensity and, (2) inelastic scattering phenomenon. Thanking you.

Regards

[Manoj Kumar]

Hi Fayiqa ma’m
All the TWDM ONTs must be colorless. The ONT transceiver must be able to tune to the correct wavelengths in upstream and downstream during end-user provisioning.
We can use a variety of techniques to control the wavelength in the upstream direction from the ONT to the OLT. Temperature is the primary parameter of control. all TWDM ONTs must be colorless. The ONT transceiver must be able to tune to the correct wavelengths in upstream and downstream during end-user provisioning.

Operators can use a variety of techniques to control the wavelength in the upstream direction from the ONT to the OLT. Temperature is the primary parameter of control.
n the long-term, it is hoped that photonic integrated circuits will provide other economical solutions to wavelength control.

In the downstream direction, thermo-controlled thin-film filters can be integrated into the ONT receiver to allow tuning. Photonic integrated circuits may provide a future solution.

[Rajguru M. Mohan]

Hi,
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.
The TWDM-PON ONU tunable transmitter is used totune its wavelength to any of the upstream wavelengths.
any techniques have been developed as candidates ofupstream laser source, including spectral slicing of broad-band sources, remote reflective modulators, and injectionlocking. The most common lasers for upstream lasersource are the directly modulated Fabry-Perot laser diode(FP-LD) and the reflection semiconductor optical amplifier(RSOA.
n addition to RSOA and FP-LD laser sources, there areother lasers such as DFB laser with temperature control(TC), DFB laser with partial TC multi-section distributedBragg reflector laser (electrical control) without cooling,external cavity laser (ECL) with mechanical control with-out cooling, and ECL with thermo/electro/piezo/magneto-optic control without cooling.

Thanks,

[Karan Ahuja]

Hi
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.
Hope this information will be of some help
Regards

[Hamza Ali Abbas Khan]

Hello Fayiqa Naqshbandi,

As far as your query is concerned i would like to suggest you to go through the paper the link of which i will attach below.
https://dru5cjyjifvrg.cloudfront.net/wp-content/uploads/2016/04/TWDM1.pdf?448a95

Hope this is helpful to you.
Thanks

[Hamza Ali Abbas Khan]

Also i would like to add that it has given various advantages of using tunable receivers and tunable transmitters.
ONU Tunable Receiver: The TWDM-PON ONU receiver should tune its wavelength to any of the TWDM-PON down-stream wavelengths by following the OLT commands. This function can be implemented by using candidate technologies such as thermally tuned Fabry–Perot (FP)
filter angle-tuned FP filter, injection-tuned silicon ring resonator liquid crystal tunable filter , and thermally tunable FP
detector.
And as far as ONU Tunable Transmitter is concerned, The ONU transmitter can tune its wavelength to any of the upstream wavelengths. The implementation technologies are distributed feedback (DFB) laser with temperature control (TC) [14], DFB laser with partial TC multisection distributed Bragg reflector laser (electrical control) without cooling , external cavity laser (ECL) with mechanical control without cooling ECL with thermo/electro/piezo/magneto-optic control without cooling.

Thanks

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