Questions on WDM Technology

• How to determine aggregate output power of a WDM?
• Spectral width wavelength to frequency conversion.
• Difference between CWDM and DWDM.
• What is Red band and Blue band?
• What is dark fibre and dim fibre?
• What are dark fibre considerations?
• How many types of optical fibres?
• Specifications of Multimode Fibre?
• How many types of Single mode Optical fibres.
• What are dispersion and attenuation coefficient of NDSF.
• If for same distance OTDR done and wavelength changed, will it show any difference in Losses?
• What is micro bending and macro bending?
• What is fibre characterization?
• Types of patch cord.
• What is Linear and nonlinear impairments
• What is Stimulated Raman Scattering (SRS)?
• What is Stimulated Brillouin Scattering (SBS)?
• What is Four Wave Mixing (FWM)?
• What is Intensity Modulation (MI)?
• What is Self phase modulation (SPM)?
• What is Cross phase Modulation (CPM or XPM)?
• How to reduce FWM impact?
• What is impact of linear and nonlinear effects in DWDM network?
• What are 3R, 2R and 1R?
• What are types of Pluggable Optics?
• What is common optical specification of Optical Transceiver (Pluggable Optics or Transponder)?
• What is fixed optics?
• If for point to point fiber link, two routers are connected and LX SFP used. If losses increased in fibre, what are possibilities to keep the link working?Want to connect client who is 300 kms apart. I don’t want to use EoSDH. I have 1000base ZX SFP. Can I send my link using 5 amplifiers.
• Types of Receivers?
• Why Receiver Sensitivity is so important for optical module?
• How many types of Amplifiers used in DWDM network?
• Raman Amplifier specification Vs. EDFA Specification.
• Difference between EDFA and Raman amplifier?
• Typical application of Raman amplifier.
• What is Dual or Double stage amplification?
• What are probable causes when second amplifier is getting low input power or no power, while first amplifier is transmitting target power in Dual stage amplifier?
• What is Hybrid Amplification?
• What is difference between Pre- Amplifier and Post- Amplifier (Booster)?
• What is power control mode and Gain control mode?
• What is effect of Amplifier gain on OSNR while reducing or increasing flat gain? (Linkedin).
• What are Specifications of Optical Amplifiers?
• What is gain tilt and Gain ripple?
• How amplifier positioned in Bidirectional Single fiber DWDM network?
• How WDM Works?
• What are typical specifications of DWDM MUX?
• What is Maximum channel capacity of DWDM channel?
• What are key attributes for selecting OADM?
• What are optical specifications of OADM?
• What is CWDM?
• What is channel equalization? What is impact of non-uniform power spectrum?
• What are probable causes when among 10 channels; one transponder at remote end is getting power below set threshold?
• How equalization can be checked?
• What is PMD?
• What is DGD?
• Is there any correlation between chromatic dispersion and PMD?
• What is Linear and nonlinear impairments?
• What is dispersion?
• What are the types of dispersion?
• What is Pilot Tone in WDM?
• How CD and PMD limits vary with channels and bitrate?
• What is FEC?
• How does FEC impact OSNR and BER value of a link?
• What is Q factor?
• Why we simulate Q rather BER?
• What is OSNR and what is its significance?
• How to improve OSNR of a link?
• At what point OSNR is max and min in a WDM link?
• What is OSC in DWDM link? What are the wavelengths used for it?
• What is the bandwidth of OSC signal?
• Where is OSC signal introduced in a DWDM link?
• What if OSC is inserted on MUX port?
• Why 3dB is crucial factor in WDM and what does it mean?
• What is dead zone and why it is created in Photonic’s spectrum?
• What is centre frequency and how is it important?
• What is channel width slot width, channel spacing and centre frequency?
• What is the modulation techniques used in current for WDM transmission?
• What is the difference between transponder and muxponder ?
• What are the type of module used for transmitter and receiver in WDM link?
• Why EDFA is considered as best for commercial use?
• How RAMAN amplifier is used in the network?
• What is the frequency band for EDFA and RAMAN?
• Whether EDFA can be used in bidirectional WDM and if yes how?
• What is composite power and how it is measured?
• How to measure composite power when all input powers are different?
• How monitoring ports work on WDM cards?
• What are the causes and source of ASE generation in WDM link?
• Do we place attenuator with EDFA amplifiers and if yes where?
• Why we put DCM in between two AMP in a WDM link?
• What is the maximum and minimum value of OSNR for a link?
• What are the different types of amplifiers available?
• What is Channel flatness and how it is important?
• Why changing power of one channel affects whole band power or composite power?
• Can you please tell me what the difference between, dB and dBm when you are trying to test fiber optic cable.
• What is ORL value? How does it matters in a link?
• What is BOL and EOL and what is the margin between them?
• Why there is ALS system on AMPs or photonic systems?
• Why is it required to create adjacencies or logical connection between MUX and Transponder and other elements in WDM network?
• What is fiber fuse and what is the cause for the same?
• What is chirp and what is it’s effect and how it affect a link?
• Why Raman is not used in place of EDFA ?
• What is Q factor ? and how it is calculated ?
• Noise figure ?
• How OSA tester works and what are different options in the test instrument ?
• Commissioning of new OCH in the network?
• Link budgeting and commisioning parameters ?
• Braggs Grating & AWG difference?
• How to test OSNR using OSA for 10G, 40G & 100G channels ?
• Soft DECISION & Hard DECISION FEC?
• What is osnr threshold for 10 / 40/ 100G?
• what is the max no. OF repeater can be used in a link?
• How alarm propogate when there is no frame structure in dwdm?
• What are the general alarms observed in a DWDM network?
• What are the performance parameters for DWDM elements.
• How DCM is used in DWDM?
• Can we use DCM in 100 G network?
• What is the channel spacing for hybrid channels(10/40/100/200) coherent and non coherent?
• Will a single mode connector work on multi-mode cable?
• How an optical power meter differs from an OTDR.
• Is it possible to convert optical fiber signal into cat5 and if yes how?
• Why do some power meters have calibration at 1300 nm while others are 1310 nm?
• What is flexgrid network?
• What is difference between CDC networks?
• What is WSS based technology?
• What is ITL used for?
• Why WDM network doesnot requires external SYNC ?
• How Extended shelf communicates in rack ?
• What are the passive and active components available in a DWDM network?
• How different modulation techniques affect technical parameters in a link?
• What are the various graphs generally used for representing WDM performance for a network?
• What if very high power launch from transmitter/OTDR with another end open.