GaAs was back-burnered because of the cost of figuring out the 4th terminal issue, and the length of time it would take for industry adoption.  POET's ability to become a market leader with the OI could end up helping fund the 4T issue in the future.  

Thank goodness for the pivot because here we are today hearing about new verticals/products seemingly every few weeks thanks to a "platform" solution.  Anyone wanna bet that LIDAR is next?