A link-budget spreadsheet can be right for the wrong reasons. Misstated aperture efficiency, an assumed receiver threshold, an underestimated pointing distribution, or an optimistic DSP power figure can each move the result materially.
What we should measure first
Begin with one controlled optical path and a known receiver. Establish calibration, record an optical power budget, and measure error performance under attenuation. Then add a second wavelength, test isolation and cross-channel interference, and repeat the measurement with realistic thermal shifts.
Only then should a free-space range be added. The measurement must isolate tracking error, atmospheric fluctuation and optical alignment from the communications layer. Otherwise failures get blamed on whichever subsystem is easiest to replace.
The first customer deliverable
For an optical-terminal OEM, a short engineering memorandum containing test setup, calibrated BER/OSNR curves, measured electrical watts, thermal limits, and known failure cases is more valuable than a speculative capacity figure.
That is how we intend to progress: simulation, controlled bench evidence, free-space test, qualified subsystem. The 10 Tb/s-class ambition remains a target until the physics and the manufacturing data agree.