They already said what's in it for them:

leverage our assets and inject non-dilutive capital into POET

allows POET to pursue a ‘fab-light’ strategy with a less capital-intensive business model

and....

At the same time, a well-funded partner capable of making investments in both DenseLight and in additional manufacturing capacity will both support the anticipated ramp of POET’s Optical Interposer and transform DenseLight into a world-class manufacturer with global market reach.  In addition to being one of its potentially largest customers, we expect to remain engaged with DenseLight and its partner over the long term for the benefit of both companies.

if there's anything else in it for POET they are misleading investors by not providing that information, which I doubt is the case. there is no hanky panky here, it is what they claim it is.

That being said, the share price is .33, and something needs to be done about that asap.