What it covers:
Why linewidth broadens at high power when the linewidth equation predicts it should narrow, and the two mechanisms behind it
κL as the design knob, and why 0.7 is the value that gets picked
How cavity length is chosen, and what going from 1.5 mm to 4 mm buys and costs
What longer cavities mean for reliability and mode stability
Why the physics is not the moat
Why maximum laser power does not decide the winner, and what "good enough" means for a CPO or NPO system
What can and cannot be concluded about Coherent, Broadcom, Sumitomo, and Applied Optoelectronics from public information
For investors and engineers who want to judge UHP laser claims themselves rather than take the consensus on trust.
Reading Part 1 first is recommended.