ITTR, you are not wrong. In the simplest of terms, in a traditional semiconductor "module", free space is the emptiness between the lenses where the photons cross.

POET's platform has no "free spaces". It is solid state, which means alignment is done by waveguides, which are components of the module, so there is no need for lenses to focus, direct and/or manage photonic movement.

Much cooler....pun intended