Sub-micron laser placement, lens alignment, fiber coupling, wavelength-multiplexing integration, hermetic sealing, thermal management, and full signal-quality calibration — that's a 1.6T module. Independent research calls this the "boring but decisive" layer: precision and yield demands rise non-linearly with bandwidth, and at hyperscale, yield gains compound. If leading-edge module demand keeps exploding, the assemblers who deliver at scale may capture more value than the market expects from an assembly business.