Predictive Software Scheduling as an Early-Warning Hint Layer for Optical Engine Thermal Drift in Heterogeneous SoIC Packaging

By Chi Fei Chung, XRM-SSD Engineering, Dollarchip Technology Inc. 

Abstract

As semiconductor scaling reaches the A16 / 2 nm node, the integration of co-packaged optics (CPO) via TSMC's Co-Packaged Optics Ultra Engine (COUPE) architecture introduces critical thermal-optical coupling challenges. Micro-ring resonators embedded in the Photonic Integrated Circuit (PIC) layer are exquisitely sensitive to temperature: a deviation of merely ±1.7 nm in resonant wavelength causes measurable Bit Error Rate (BER) degradation. We propose XRM-SSD V24, a physics-aware scheduling layer that models inference-load density 20–50 ms before execution and issues early-warning hints to the COUPE bias-control firmware, enabling pre-emptive thermal compensation. Empirical validation over 90,000 inference steps yields a thermal-load correlation of R² = 0.9911 and wavelength drift below 0.36 nm — less than 21% of the TSMC tolerance budget. A full Thermal Resistance Fingerprint characterization further confirms R_th = 0.45 °C/W, thermal time constant τ = 80 ms, and thermo-optic coefficient 0.0852 nm/°C across five discrete load states (Idle to Peak). Memory stability improved from 166 MB/hr to zero leakage. We establish a formal domain separation between deterministic software scheduling and continuous physical thermal dynamics, ensuring physics-consistent claims suitable for peer review.

Index Terms — Co-packaged optics, thermal resistance fingerprint, predictive scheduling, photonic integrated circuits, TSMC COUPE, heterogeneous integration, SoIC, 2 nm node, thermo-optic coefficient, wavelength stabilization, inference optimization.

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