PON

[deepak jha]

hi all,

In case of Passive Optical Networks (PON) is it possible to split the power unequally among various optical network units or is it necessary to split the power equally ?

[Rahul Tiwari]

hi DEEPAK,

I believe you can split the power equally using splitter…

Regards

[FAYIQA NAQSHBANDI]

HELLO DEEPAK..
As far as i know you can only split power i dont know if we can split it equally or unequally because there is no such specification..I hope you understand what i mean.

Regards

[nagesh kuknoor]

Hello Fayiqa,

I seem to agree with you. In optisystem power is divided equally. I hope this should help Deepak
Regards
Nagesh

[Rajguru M. Mohan]

Hi Deepak jha,

I would suggest you please refer to optisystem component library pdf.
Fiber optic splitter is a key optical device in passive optical network (PON) systems,
also known as a passive optical splitter, which splits the optical signal power evenly into all the output ports.
Splitter component splits evenly the signal input power to different output ports.
which means power is evenly distributed into different output ports.
It is based on principle of FBT splitter makes two (two or more) fibers removed
the coating layer gather in a certain way, stretched to both sides under the
heating zone at the same time, form a double cone’s special waveguide structure
finally for getting a different splitting ratio via controlling length of the fiber torsion angle and stretch.
OPTICAL power splitter (OPS) is one of the most important
components in an optical communication network.
In the last decade, optical splitters based on fiber couplers and
planar lightwave circuit (PLC) have been highly developed.

Thanks

[FAYIQA NAQSHBANDI]

HI RAJGURU..

I agree with you that may be help him to some extent..

Regards

[Rajguru M. Mohan]

Hi,
the above Splitter was conventional one, but in optisystem we use the conventional one .
That is the splitter which splits equal power to all outputs.
But due to advancement in technology we have variable Optical Power Splitter which
can provide benefits such: It can allocate the optical
power of each ONU dynamically by changing its own power
split ratio. It will improve network scalability, increase optical
power efficiency, provide better network reliability, and reduce
investment risk and find applications in self-healing ring which is a
popular protectio which can resume traffic
from a failure automatically in real time without manual intervention
. However, when a fixed OPS is used, the power
difference among nodes will be too big to accept.

Thanks

[FAYIQA NAQSHBANDI]

HI ALL..

Thank you RAjguru for the valuable information..I appreciate your efforts.

Regards

[deepak jha]

Hi Rajguru,

Thanks for the information.. Your efforts are highly appreciated…

Regards

[nagesh kuknoor]

Hello,
I agree with Deepak. Rajguru has been very very helpful throughout. I appreciate too

Regards
Nagesh

[Ankita Sharma]

Hi Rajguru,

Thanks for the information…

Regards
Ankita

[Rajguru M. Mohan]

Thank you Fayiqa, Deepak, nagesh for your agreement and appreciations.

[Rajguru M. Mohan]

Hi,
We have different types of splitter out of these i am trying to sxpalin two types of splitters.
Their advantage and disadvantage:
PLC – Planar Lightwave Circuit Splitter

Advantages

Suitable for multiple operating wavelengths (1260nm – 1650nm); unstinted.
Equal splitter ratios for all branches.
Compact configuration; smaller size; small occupation space.
Good stability across all ratios.
High quality; low failure rate.
Disadvantages

Complicated production process.
Costlier than the FBT splitter in the smaller ratios.

FBT – Fused Biconical Splitter

Advantages

The product is well-known and is easy to produce, thus reducing cost of production.
Splitter ratios can be customized.
Can work on three different operating bands (850nm, 131 Onm, and 1550nm).
Disadvantages

Restricted to its operating wavelength.
Because of errors in equality insertion loss, the maximum insertion loss will vary depending on the split and increase substantially for those splits over 1:8.
Because an exact equal ratio cannot be ensured, transmission distance can be affected.

Thanks,

[Karan Ahuja]

Also DWDM PON architectures are of high interest and are on the way to becoming commercially realized, the bandwidth can be substantially scaled up compared to common PON networks concepts. AWG based structures for MUX/DEMUX applications in WDM-PON networks are ideal, adapting perfectly to PON architectures, allowing cyclic character and are leveraging the state of the art PLC processing techniques. The recent progress of AWG design concepts for DWDM PON architectures and their athermal packaging techniques, now suitable for mass production in low cost manufacturing countries, are discussed. The state of the art reliability performance for industrial and in particular DWDM PON applications are demonstrated. AWG based DWDM PON network architectures are elaborated comparing other existing PON network concepts.

You may refer to this paper in this regard
http://ieeexplore.ieee.org/xpl/login.jsptp=&arnumber=4054038&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumbe

[Karan Ahuja]

I want to add that the integrated semiconductor optical amplifier (SOA) with a reflective electro-absorption modulator (REAM) is a promising candidate for the colorless optical network unit in a wavelength-division-multiplexed passive optical network (WDM-PON), due to its low chirp and wide bandwidth. However, 40 Gb/s operation of REAMs (bandwidth <; 20 GHz) still encounters severe intersymbol interference. Furthermore, Rayleigh backscattering (RB) and discrete reflections cause strong beat noise in WDM-PONs with single-fiber loopback configuration. In this paper, we present two novel techniques based on electrical equalization for a 40-Gb/s single-feeder WDM-PON based on SOA-REAM. The first method is to employ partial-response (PR) signaling and a noise predictive maximum likelihood (NPML) equalizer at the upstream receiver. The other one combines correlative level (CL) pre-coding with partial-response maximum likelihood (PRML) equalization. We experimentally demonstrate a 40-Gb/s uplink of 20 km using a 20-GHz SOA-REAM in a WDM-PON by both PR-NPML and CL-PRML. The results also verify the superiority of PR-NPML over the previously reported equalizers. Moreover, compared with PR-NPML, CL-PRML further improves the system performance. Experiments prove that the tolerance to beat noise and the receiver sensitivity are enhanced by 4 dB and 0.8 dB, respectively, at a bit error ratio of 2 × 10-4.

Here is the link of this paper
http://ieeexplore.ieee.org/xpl/login.jsp?tp=&arnumber=6360172&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6360172

[Rajguru M. Mohan]

hi,
The simplest couplers are fiber optic splitters. These devices possess at least three ports but may have more than 32 for more complex devices. Figure 1 illustrates a simple 3-port device, also called a tee coupler. It can be thought of as a directional coupler directional coupler. One fiber is called the common fiber, while the other two fibers may be called input or output ports. The coupler manufacturer determines the ratio of the distribution of light between the two output legs. Popular splitting ratios include 50%-50%, 90%-10%, 95%-5% and 99%-1%; however, almost any custom value can be achieved. (These values are sometimes specified in dB values.) For example, using a 90%-10% splitter with a 50 µW light source, the outputs would equal 45 µW and 5 µW. However, excess loss hinders that performance. All couplers and splitters share this parameter. Excess loss assures that the total output is never as high as the input. Loss figures range from 0.05 dB to 2 dB for different coupler types. An interesting, and unexpected, property of splitters is that they are symmetrical. For instance, if the same coupler injected 50 µW into the 10% output leg, only 5 µW would reach the common port.

Thanks,

[Rajguru M. Mohan]

Hi,
An optical splitter is a passive optical fiber tributary device that connects an optical line terminal to an optical network unit. It can transmit packets using time division multiplexing (TDM) in the downlink and gather packets using the time division multiplexing access (TDMA) protocol in the uplink. Optical splitting ratio ranging from 1:2 to 2:64.
With the split ratio ranging from 1:2 to 2:64, the optical splitter series can be installed in a connecting box, splice box, or optical division box for fiber splitting, while the clearly-labeled optical route identifiers facilitate easy maintenance.
Most Splitters available in 900µm loose tube and 250µm bare fiber. 1×2 and 2×2 couplers come standard with a protective metal sleeve to cover the split. Higher output counts are built with a box to protect the splitting components.

Thanks

[Karan Ahuja]

Hi.
I would like to mention that the wavelength-division-multiplexed passive optical network (WDM-PON) has been generally regarded as a promising solution to the next-generation access network that will be required to deliver services over 40 Gb/s. However, fiber dispersion often limits the capacity and reach of WDM-PONs. Compared with dispersion compensation fiber, which is bulky and expensive with significant power loss, digital signal processing is a more suitable way to mitigate chromatic dispersion in PONs. Furthermore, expense is a critical concern in the WDM-PON, due to its need for a large number of lasers and a complex wavelength control mechanism. One practical solution is to reuse the downstream (DS) signal as the carrier for the upstream (US) modulation. In this case, the residual DS signal after remodulation can seriously degrade US transmission. In addition, system performance can be deteriorated by the unwanted reflection as uplinks and downlinks share one wavelength. In this paper, we propose using modified duobinary (MD) coding in the DS to improve its dispersion tolerance and reduce the crosstalk between DS and US induced by remodulation and reflection. MD is a correlative level code that can reduce signal bandwidth and achieve DC balance. We demonstrate a 15 km WDM-PON delivering a 40 Gb/s MD-coded signal in the downlink and a 10 Gb/s on-off keying signal in the uplink. Compared with no coding, the maximal allowable extinction ratio of the DS signal (ERd) is improved by 4 dB. Moreover, the reflection tolerance of the uplink and downlink is enhanced by 5 and 4 dB, respectively. In addition, investigations on the use of different equalizers in the DS to further suppress fiber dispersion confirm that the superior performance of nonlinear equalization in MD-coded transmission and that the network reach can be extended to 25 km by a nonlinear decision feedback equalizer.
Hope this will give you an idea.
http://ieeexplore.ieee.org/xpl/login.jsptp=&arnumber=6645106&url=http%3A%2F%2Fieeexplore.ieee.org%2Fstamp%2Fstamp.jsp%3Ftp%3D%26arnumber%3D6645106

Thanks

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