In this connected world, our data connectivity is constantly being pushed to transport higher bandwidth and further distances…and need to be compatible with existing platforms… and limiting power usage… and maintaining a small form factor to maintain port density…PHEW! This is definitely a tall order for pluggables; but technology marches onward.
Without using amplifiers and filters to compensate for dispersion effects, as your bandwidth increases, the maximum distance your signal can travel decreases. A 1Gb signal can reach hundreds of kilometers. A 10Gb signal drops off to an effective range of about 80km, and 25G and 100G signals have run about 40km. The world’s demand for higher speed connections between metro areas however, has driven innovation and a demand to
take 100G further.
Solutions to Push the Distance
In the push to break the 10G limit for 80km, you’ve probably heard of coherent optics. The idea is to combine multiple paths to high speed transmission at greater distances into one transceiver. Coherent solutions use digital signal processing to correct for polarization mode dispersion (PMD) and chromatic dispersion (CD), DWDM channel widths, and forward error correction (FEC) to maintain signal integrity over a distance. These transceivers can be used with DWDM passive filters to get a huge amount of bandwidth over single mode fiber. When amplified, the coherent option can get you hundreds or thousands of km! Unfortunately, these methods come with some downsides. Due to the physical space required in the transceiver, as well as the power availability, currently only CFP and CFP2 have coherent options. It is also important to know that DSPs from different manufacturers are not compatible, so the coherent optics on both sides need to be carefully selected. There’s also a matter of cost, which when framed against cost-per-bit is still attractive, may be prohibitive depending on your budget.
Taking another approach, QSFP28-ZR4s are now available to take 100G to the 80km mark. The ZR4s use lasers producing 4 LWDM signals (1296 nm, 1300nm, 1305nm and 1309nm) that are multiplexed into a single signal onto the fiber. On the remote side, this composite signal is amplified using an integrated SOA (Silicon Optical Amplifier) and demultiplexed. When this technique is combined with forward error correction, the reach meets the 80km goal. This method fits into the QSFP28 form factor and is operated within standard power availabilities, which is really impressive. The best part is that these ZR4 parts are compatible with the existing QSFP28 100G platforms. The performance over distance, low power consumption, form factor density, and platform compatibility already has the market queued up for QSFP28-ZR4s.
Embracing New Technology
There’s always a risk in embracing any new technology and of course. Having Integra Optics as a trusted partner, with unmatched support and lifetime warranties on our transceivers, makes all the difference. Suppliers are eager to offer QSFP28-ZR4s, but Integra Optics offers components that are rigorously tested and are top quality, meeting or exceeding OEM specifications – without voiding your platform warranty! Even though the costs of these new transceivers are much friendlier, the investment in your bandwidth expansion demands quality and reliability.