The laser is off-chip, originaing from an external source, since silcon cannot lase. It's not truly an monolithically integrated opto-electronic solution.

Also, there are no indications of cost comparisons. With the laser off-chip, packaging, assembly and testing all add to the cost equation.

While there are many potential competing advances occurring, the bottom line will always be economics as a function of yield. Can the solution scale to commercial production in a cost efficient manner? There are not enough details on DARPA's innovations to make this assessment.