the difference in raw wafer cost (maybe 75 cents per die) is not material to the finished package, where P[o]ET is considerably less expensive*.

the real cost is in the masks anyway (where P[o]ET also wins).

when you get to full-blown POET (optical mix), we win with CoGS by a landslide, since waveguide optics are in-built vs. having to otherwise glue fibres in (at about $30 apiece).

GLTA,

R.

* - that's without even counting the end-use power/performance benefits ... this is just mfg. assembly & test ... ie, taking advantage of the ability to put digital and analog on the same chip.