100G QSFP28 Single-Lambda vs. traditional 100G QSFP28 with 4-Channels
What is "Single-Lambda" and why should I use it?100G transmission is common in today's networks. Typically these transceivers are based on 4 parallel lanes that operate at speed of 25G each and modulated with NRZ (Non Return to Zero). For single mode fibre each lane has its assigned wavelength (like CWDM4 or LR4) as well as one of the four lasers and receivers.
Standardised by the 100G Lambda MSA, 100G single lambda transceivers process these 4 x 25G electrical signals from the host side via a built-in discrete DSP (Digital Signal Processor) using PAM4 (4 level Pulse Amplitude Modulation) - instead of NRZ - and feed the new modulated signal into one single laser at the speed of 100G. That reduces the cost for optical components, etc.
Specified for up to 500m, single-lambda started with 100GBASE-DR; followed by 100GBASE-FR for up to 2km and 100GBASE-LR for distances up to 10km.
Comparison Single-Lambda 100G vs. 100G with integrated Mux
|QSFP28 FR Single-lambda (2km)||QSFP28 CWDM4 (2km)|
|Working Mode||Modulation Scheme PAM4||NRZ with integrated 4-ch Mux/Demux|
|FEC Requirement||BER 5E-5: FEC in Host required for BER 1E-12|
|Power Consumption||~ 3.5 W||~ 3.5 W|
|Receiver||PIN ROSA||PIN ROSA|
|QSFP28 LR Single-lambda (10km)||QSFP28 LR4 (10KM)|
|Working Mode||Modulation scheme PAM4||NRZ with integrated 4-ch Mux/Demux|
|FEC Requirement||BER 5E-5: FEC in Host required for BER 1E-12||no additional FEC needed|
|Power Consumption||~ 4W||~ 3.5W|
|Receiver||APD ROSA||PIN ROSA|
But why is single-lambda so attractive?
A scenario from the datacenter as an example: with 100G single-lambda it is possible to break a single 400G signal into a 4 x 100G breakout.
So aside from lower costs for the single-lambda transceiver, this technology paves the way to take your infrastructure to 400G in the near future.
Summary and additional interoperable 400G products400G DR4 to 4x 100G DR
400G FR4 to 4x 100G FR
400G LR4 (under development) to 4x 100G LR