My 2 cents:
Any competitor of POET would - like POET, protect their IP by filing of patents. Even with heavy NDA and black curtains to hide things this is a must.
And I guess POET (our good doctor GT) as well as some of us do have a quite good picture of the patents in this field of application. This is part of the homework you do in this field of R&D!
So to me it seems the probability that there is a hidden competitor out there in the dark - is very - very small.