So basically the speed has been maxed out at 100G using PAM4. VCSEL structures are large and to get to 800G you need to connect 8 of these VCSELs in a surface mount as opposed to planar edge mount unless inverted as a flip chip (something POET excels at). POET's biggest attribute is  connectivity so the potential is there. But I do wonder if others are doing the same? Using InP to build a new VCSEL design for O band and C band. VCSEL wavelength can also be adjusted with quantum dots.

Very interesting and I think POET has a good opportunity here.