Lightwave Logic Inc (LWLG)

[Photonics_Guy]

Limitations of Adding Parallel Paths to a Photonics Transceiver

One thing that you'll see mentioned in various Photonics companies' publications is the idea of "parallelism", i.e., adding multiple parallel paths or "lanes" to a transceiver to increase data rates. Sounds really good, but the approach has some limitations that are rarely mentioned.

There seems to be a common perception that multiple parallel lanes of 4, 8 or even 16 lanes will solve the problem of obtaining ever higher data rates. That may be true to a limited degree, BUT there are big issues in getting highly parallel systems to work.


Conventional method for legacy technology to achieve higher data rates is to add parallel lanes

A few things to keep in mind:

1. Each time the power through a particular lane is halved, you get 3dB optical loss, which translates to 6dB of RF loss (RF loss is always 2X optical loss)

2. Two channels have half the power of one lane, four has half the power of two, eight is half the power of four, etc.

3. Consequently, multiple lanes have much lower power (dynamic range) than few lanes.

4. This is compounded by higher order modulations like PAM4 and PAM8, etc. The spacing between logic levels is smaller for higher order modulations, and therefore, is more susceptible to perturbations in signal levels, resulting in significantly higher bit-error-rates (BER).




5. Complexity: Getting all those channels to be precisely time aligned and balanced in amplitude adds complexity and cost to the system.

For these reasons, I believe a practical limitation to parallelism will be 4, possibly 8 lanes. The losses and error rates of large number of lanes will simply be too high to overcome. This is the big limitation to SiP IMO. SiP only solutions will find it very hard to scale the performance required to hit the higher data rates.


The Lightwave Advantage!

In conclusion, Lightwave Logic powered transceivers with the blindingly fast data rates enabled by their proprietary polymers (150Gbps per lane) are able to provide 800Gbps right now. This gives components that embed Lightwave IP inside a tremendous performance advantage over competitors products.

PG