It's hard for people to understand what a departure POET is without understanding how things are done today. Last week Suresh presented the POET platform at the Synopsys Photonic Symposium and the presentation has been made available on youtube:

(76) POET Technologies Featured at Synopsys Photonics Symposium - YouTube

That link was posted here by foxy but it did not get the forum's attention the way it should have.

Clearly this was an industry level presentation and as such a lot of very meaningful detail was provided. I am just starting to feel better after having COVID which we caught at a Bryan Adams concert a week ago Friday. So I have been slow to provide any commentary of that presentation.

I will comment for now on what I believe is a major step forward in the ability to simplify the ability to route light on and off the POET optical engine. One of the major keys to POET’s success is the ability to couple light efficiently both into and out of fiber through in-plane butt coupling.

In silicon photonics today the preferred approach for coupling fiber into and out of a PIC is through the use of waveguide grating couplers at the top surface since it provides the flexibility to place them at specific locations on the PIC where they need to be. It is however a leaky solution when compared to the coupling efficiencies that POET has achieved through butt coupling. Edge coupling typically does not provide the ability to perform wafer scale testing since access to the waveguides are at the edge of the wafer. Again POET has a solution for this through the loopback waveguides which allow a path from the transmit to the receive through the loopback waveguides which are not part of the final die and are removed during dicing.

The clip below gives you an idea of how awkward testing is at the surface through grating couplers. 

(76) Autonomous Silicon Photonics Measurement Assistant | FormFactor - YouTube

So why does POET butt couple fiber at the edge? The optical interposer provides optical waveguides sandwiched between electrical waveguides. The receive circuit comes in at a top level waveguide and is routed to the vertical mirror where the light is efficiently reflected up to the surface where the photodetector has been flip-chipped to receive the signal. An ingenious approach that provides excellent coupling efficiency and a level of placement freedom/flexibility that does not exist in silicon photonics today.

Go to time 23:00 in Suresh’s presentation. I have got to be honest I was extremely excited by his presentation and felt that this is it. The holy grail is being described.

(76) POET Technologies Featured at Synopsys Photonics Symposium - YouTube

So let's get past whatever this market condition is and move forward. It would have been great if we could have snagged the Institutional investors needed before the uplist but that did not happen at that time.  But I think they are getting closer.