Equation 8 · An Optical Fabric Turns Off-Package Memory Into an Extension of the Die
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Symbol P_opt
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subscript
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What the article says around this equation
The amortization term in that denominator matters more than it looks at first pass. A fixed integration cost — the extra laser sources, the photonic-PIC yield loss, the switch die itself — divided across a single module looks catastrophic; divided across sixteen thousand modules in a hyperscale fleet looks close to free. That is precisely why belongs in the model as a scale-dependent term rather than a single constant: the same fabric can fail the copper baseline at pilot volumes and clear it easily at fleet volumes, and a headline efficiency number has every incentive to quote whichever scale flatters it without ever stating which one that was. Neither Celestial AI’s nor…
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The amortization term in that denominator matters more than it looks at first pass. A fixed integration cost — the extra laser sources, the photonic-PIC yield loss, the switch die itself — divided across a single module looks catastrophic; divided across sixteen thousand modules in a hyperscale fleet looks close to free. That is precisely why belongs in the model as a scale-dependent term rather than a single constant: the same fabric can fail the copper baseline at pilot volumes and clear it easily at fleet volumes, and a headline efficiency number has every incentive to quote whichever scale flatters it without ever stating which one that was. Neither Celestial AI’s nor Marvell’s public disclosure states a deployment scale for any claim about this technology at all — which means even a future wattage disclosure would still need to arrive paired with a stated deployment volume before this index could be computed honestly rather than cherry-picked at whatever scale makes the ratio look best.
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