Search Results for 'wdm'

[Karan AhujaSpectator]

Hello,
I want to mention that in conventional DQPSK receivers a pair of onebit delay asymmetric Mach-Zehnder interferometers (AMZI) are used: one for the in-phase (I), and one for the quadrature (Q) component. Similar to binary DPSK3, a narrow optical filter can be used instead of each AMZI 4. The frequency response the optical filters should approximate the main lobe of the frequency response of the constructive port of the AMZI. By tuning the central frequency of the filter either the I or Q component of the DQPSK signal can be demodulated. We will call such a receiver a narrow filter (NF) receiver. We experimentally demonstrate in this paper that a single arrayed waveguide grating (AWG) can be used
to simultaneously demodulate the in-phase (or quadrature) component of a comb of DQPSK signals. It can be seen how the AWG filter approximates the main lobe of the theoretical response of the AMZI. The use of AWGs for WDMDQPSK signals represents a big advantage in terms of component counts.
Hope this helps.
regards

[umer ashraf waniParticipant]

https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwijne_P08XMAhVD26YKHdUuDBIQFgglMAE&url=http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0030402611005845&usg=AFQjCNHSjyTJRViNNegkbuAPR8Dq1ycaoQ&sig2=kx7PKiGnGoy3o9NdtMyFBg
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwijne_P08XMAhVD26YKHdUuDBIQFggtMAI&url=http%3A%2F%2Fieeexplore.ieee.org%2Fiel5%2F2220%2F28659%2F01283616.pdf%3Farnumber%3D1283616&usg=AFQjCNGJhxt0k0mu3ACeSCvDK2s_bku1Rg&sig2=N1-vMGSeF2klR3xDHvl8_w
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=8&cad=rja&uact=8&ved=0ahUKEwijne_P08XMAhVD26YKHdUuDBIQFghSMAc&url=http%3A%2F%2Fwww.copl.ulaval.ca%2Ffileadmin%2Fcopl%2Fdocuments%2Fdocuments%2FPublications-PDF%2FRusch%2Fconf89.pdf&usg=AFQjCNGUvMGgUk7JIBh64iAOpT3RRtzyNQ&sig2=v0_btoqd4eaRLL23UR2HMw
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=11&cad=rja&uact=8&ved=0ahUKEwiv3Irj08XMAhUIx6YKHTlcD104ChAWCBowAA&url=https%3A%2F%2Fwww.vde-verlag.de%2Fproceedings-en%2Fgs_proceeding%2F%3Fdocid%3D563042311&usg=AFQjCNEbiAaihmuTMbRvDMzkNtZIKOVIsg&sig2=dVWSA5sNGqWC71KOEG68qg&bvm=bv.121421273,d.dGY
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[Hamza Ali Abbas KhanParticipant]

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

[Hamza Ali Abbas KhanParticipant]

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 KhanParticipant]

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.

[Hamza Ali Abbas KhanParticipant]

Hello Marvi
I agree with most of the replies. I want to add that the hybrid WDM/multibeam FSO network has provided a significant improvement in the link distance, received optical power, geometrical loss, and scalability. The network performance has been analyzed, and the study concludes that a maximum channel spacing beyond 0.4 nm is applicable for this network. The power receiver sensitivity difference of the receiver for different wavelengths at a BER of 10^(−9) was noted to be a small value, which is approximately less than 1 dB. Meanwhile, in terms of scalability, four users can access data each at 1.25 Gb/ss, which is considered sufficient compared to conventional multibeam technique accessing data to only one EU. The hybrid WDM/multibeam FSO network can be a good candidate to solve the last mile problem and the rapid increase in capacity demand without requiring new FSO transceivers. At the moment, the evaluation is going on for a real-time system operating in heavy rain as compared to simulation presented here. In the future, increasing the capacity of the hybrid WDM/multibeam FSO network can be studied and implemented to reach up to 32 channels.
The link provided by Mr. Karan should help you.
Thanks

[Karan AhujaSpectator]

I also want to mention that in the WDM-based access, the bandwidth demand has increased rapidly; thus, it is a potential solution for future data transport with regard to all optical wide area networks . In fiber optics communication, WDM is well known and used extensively. Several single-beam FSO WDM transmission systems have been successfully demonstrated where the different wavelengths are carried by one beam. Even though more than one wavelength is used to increase the data rate, after all, this system lies under a single-beam attenuation affect. In the current study, the performance and applicability of the four-beam FSO system in rainy weather are proposed and investigated using WDM. The study is conducted based on simulation using on-site attenuation and rain intensity measurements. It considers the received power, geometrical losses, and atmospheric losses due to heavy rain.
I hope this is helpful to you
Regards

[Karan AhujaSpectator]

Hello
I want to mention that multibeam free-space optics (FSO) is a promising technique to overcome atmospheric attenuation due to tropical rain and to fulfill the growing demand for increased communication bandwidth and scalability. In this study, a hybrid four channel 1.25-Gb/s WDM/multibeam FSO network having four wavelengths with standard downlink channel spacing of 0.8 nm (100 GHz) is proposed. The hybrid WDM/multibeam FSO technique improved the performance of an FSO link in terms of the received power, link distance, data rate, and scalability. The proposed technique provided access data to four end users, each at a data rate of 1.25 Gb/s along an FSO link distance of 1,100 m.
I am attaching a link of paper. This may help you
http://link.springer.com/article/10.1007%2Fs11107-014-0482-y
Regards

[umer ashraf waniParticipant]

go throgh these links
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=6&cad=rja&uact=8&ved=0ahUKEwiN0JS6xcTMAhWIGo4KHSsOBsgQFgg-MAU&url=http%3A%2F%2Foptiwave.com%2Fforums%2Ftopic%2Fmultibeam-fso%2F&usg=AFQjCNFpL72tOKj0-X4h6lm1oSUX3mQlHQ&sig2=xgpqyuUAv_2bgWYP9XP0Fw
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0ahUKEwiN0JS6xcTMAhWIGo4KHSsOBsgQFggcMAA&url=http%3A%2F%2Fwww.sciencedirect.com%2Fscience%2Farticle%2Fpii%2FS0030402611003408&usg=AFQjCNFwX6q6T_zfS_UIc_Q5JVyFxv6d0A&sig2=yNCUTQ0ue67xQ7ic9zkhzQ
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&cad=rja&uact=8&ved=0ahUKEwiN0JS6xcTMAhWIGo4KHSsOBsgQFggkMAE&url=http%3A%2F%2Flink.springer.com%2Farticle%2F10.1007%252Fs11107-014-0482-y&usg=AFQjCNE6Bef72zGKSrFXiaPPNaEWhdZzTQ&sig2=Ghx0N3D4XIUR6KI39pDobA
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=3&cad=rja&uact=8&ved=0ahUKEwiN0JS6xcTMAhWIGo4KHSsOBsgQFggtMAI&url=http%3A%2F%2Fdl.acm.org%2Fcitation.cfm%3Fid%3D2747262&usg=AFQjCNHCiBjK5fZhNKqG_Ob6KsEgq9hd1w&sig2=ascXp_yt7FYRftLrsSciDg
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&cad=rja&uact=8&ved=0ahUKEwiN0JS6xcTMAhWIGo4KHSsOBsgQFgg8MAQ&url=https%3A%2F%2Fwww.researchgate.net%2Fpublication%2F273917945_Hybrid_WDMmultibeam_free-space_optics_for_multigigabit_access_network&usg=AFQjCNGiU_y8Pw4CkWywa2H3qsOXrwysEA&sig2=XsAa9rwVf0oJuCNQrxzZAA
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=11&cad=rja&uact=8&ved=0ahUKEwibq5jdxcTMAhXVBo4KHbuTDkI4ChAWCBowAA&url=http%3A%2F%2Fwww.academia.edu%2F15636180%2FHybrid_WDM_multibeam_free-space_optics_for_multigigabit_access_network&usg=AFQjCNGsqU0DmjCIcEbPnsroyrjWnLnT6Q&sig2=r9SddiXGB7IEYEhOxG4UWQ&bvm=bv.121421273,d.c2E
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=14&cad=rja&uact=8&ved=0ahUKEwibq5jdxcTMAhXVBo4KHbuTDkI4ChAWCCcwAw&url=http%3A%2F%2Flink.springer.com%2Fcontent%2Fpdf%2F10.1007%2Fs11107-014-0482-y.pdf&usg=AFQjCNEDsR2HgZjUZe1eeAxVM8N_1kO6Rg&sig2=03ccNn01f4LQYE4T6AJ3EA&bvm=bv.121421273,d.c2E
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=16&cad=rja&uact=8&ved=0ahUKEwibq5jdxcTMAhXVBo4KHbuTDkI4ChAWCDUwBQ&url=http%3A%2F%2Fijarece.org%2Fwp-content%2Fuploads%2F2015%2F05%2FIJARECE-VOL-4-ISSUE-5-1125-1131.pdf&usg=AFQjCNFksFkPC-0RQY92-yeFexM0RzT5uA&sig2=iEmxNm2y3LxLWOFMdnn1MA&bvm=bv.121421273,d.c2E
https://www.google.co.in/url?sa=t&rct=j&q=&esrc=s&source=web&cd=18&cad=rja&uact=8&ved=0ahUKEwibq5jdxcTMAhXVBo4KHbuTDkI4ChAWCD4wBw&url=http%3A%2F%2Fcsmaster.sxu.edu%2Falzoubi%2FFSO%2520Presentation%2520Phillipps.ppt&usg=AFQjCNGb7BcMpAww-Pfrqs4gqr5EcfXaQQ&sig2=FqLqMGIVK4rvX9zav6PSvw&bvm=bv.121421273,d.c2E

[Karan AhujaSpectator]

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

[Karan AhujaSpectator]

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

[Karan AhujaSpectator]

Hi Dhiman
I agree with Rajguru that Practically, it has been demonstrated numerically and experimentally that the conventional nonreturn-to-zero (NRZ) modulation format is superior compared to the return-to-zero (RZ) modulation when dealing with large WDM systems, as RZ modulation causes a significant Eye Closure Penalty near end channels. The results obtained in this tutorial will be used to compare the Eye Closure Penalties for both NRZ and RZ cases, as well as the effects of nonlinearities. The advantage of RZ format in terms of transmission distances was recently demonstrated in a long-distance wavelength division multiplexing (WDM) transmission experiment though most WDM transmission experiments conducted so far have used NRZ formats .
WDM signals, which were initially NRZ but modified before transmission, were successfully transmitted over transoceanic distances in a recirculating loop. Time-division multiplexing (TDM) transmission experiments, of course, use RZ signal formats, which allow optical MUX-DEMUX to be easily carried out.
Hope you find it helpful.
Regards

[Karan AhujaSpectator]

Hi all
I agree with Hamza Ali and Rajguru that there are three basic types of PON as APON, BPON and GPON. The use of ATM-based PON (APON and BPON), the achieved upstream and downstream aggregate bandwidths were in the order of 155 Mbit/s up to 622 Mbit/s. Later, the use of time division multiplexing (TDM) permitted achieving capacities around 1.2 Gbit/s and 2.5 Gbit/s (downstream & upstream) according with the ITU-T G.984 G-PON standard. Advanced high-speed TDM based optical access systems up to 10Gbit/s for downstream and 2.5 upstream (XG-PON1) or 10Gbit/s/ for both downstream and upstream (XG-PON2), according with the ITU-T G.987 G-PON standard, have been developed and some field trials have been reported. Currently, standardized specifications by ITU exist for ATM-based PON (APON and BPON), gigabit-capable PON (GPON) and XG-PON
and Ethernet PON (EPON) and 10G-EPON by IEEE.Further research are going towards Next Generation PON: NGPON1 and NGPON2. Hybrid TDM and WDM PON are latest type of PON recommended by ITU-T.
Hope this is helpful
Regards

[Karan AhujaSpectator]

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

[Karan AhujaSpectator]

The TWDM-PON ONU tunable transmitter is used to tune 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 injection locking. The most common lasers for upstream laser source 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 are other lasers such as DFB laser with temperature control(TC), DFB laser with partial TC multi-section distributed Bragg 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.