Some may recall in 2017 when I posted a video clip of how Kaiam Corporation used a micro mechanical system (MEMS) to actively align a lens to couple a light source into a PIC. It still had to be aligned one lens at a time but it used MEMS to align and fix the position with solder. It again required individual  work stations where operators had to manually adjust the position of the lens one at a time but the assistance of a MEMS system increased the accuracy and speed over existing systems but it was still very slow. Kaiam Corporation won a PIC International award for the improvement that process brought to Silicon Photonic Integration.

It was not enough and is a good example of Suresh’s statement at Needham:

At the end of the day, as Vivek always tells me, there’s just been so much new stuff in optics that just hasn’t kind of worked out.          

There has never been anything like this before and I have given a lot of thought to what has ultimately made this possible.  We have heard Suresh talk about innovations being at the forefront of successful tech companies.

The ability to flip chip devices to enable low loss high speed electronic connections is a well-established process with high speed pick and place tools and several bonding techniques available. Electrical connections do not require extremely precise placement for a good connection. We know that the same is not true for connecting a beam of light that is significantly more narrow that a human hair. And is probably why no has ever thought to do this before.

First off you need a material set that can be deposited at low temperature onto silicon without causing any wafer buckling. Next the material set has to have the ability to be processed in forms that can precisely shape the light beam in order to achieve very accurate light coupling. Next a method to align the beams of light to precisely match the positions of the optical chip and the waveguide or fiber.

So what did Suresh do? He had the waveguide material that made possible the fabrication of the mux and demux in an arrayed waveguide with no requirements for free space optics. And flip chip architectures was very much part of his history.

So to flip chip a photonic chip it had to be extremely precise in its placement  to   couple a tiny beam of  light  from  one medium to the  next, We can see in greater detail  for  the first time the mating features to  create this alignment accuracy on slide 9 of the Needham the presentation. These mating features are identified as Self Aligned and Mechanically Interlocking Fiducials. POET has repurposed the accuracy of the semiconductor process to make very small features with extreme precision and have turned it into a LEGO set. When the hundreds of optical dies have been accurately placed into position on the wafer by pick and place tools they then become precisely fixed into place by melting the solder bumps which allows the fiducials to mate at precisely the correct placement and that is called mass reflow which occurs simultaneously across hundreds of die in one step.

Now think about Kaiam who won the PIC award at PIC International in 2017.

For anyone wanting to look at Kaiam’s history it certainly is interesting: https://en.wikipedia.org/wiki/Kaiam

POET management are well grounded in how they see the POET Optical Interposer Platform shaping industry going forward. And I truly believe that their confidence is very well-placed.