Strengthening optical and photonic metrology through robust uncertainty evaluation and international intercomparisons

Advances in optical and photonic technologies continue to redefine the limits of precision in dimensional metrology, enabling ultra-sensitive measurements in spectroscopy, frequency metrology, and nanoscale characterization. As measurement systems become increasingly complex, the reliability of their results critically depends on rigorous uncertainty estimation and on the global consistency ensured through international intercomparisons. This contribution highlights how expert-driven uncertainty analysis and structured comparison campaigns together reinforce the foundations of modern metrology. Recent work on Brillouin spectroscopy using scanning tandem Fabry-Pérot interferometers has demonstrated the importance of detailed uncertainty evaluation when extracting small frequency shifts, accounting for instrumental finesse, scan linearity, and noise contributions. Likewise, the uncertainty assessment of phase-noise performance in high-frequency optoelectronic oscillators illustrates the interplay between optical, electronic, and environmental parameters in advanced hybrid systems. At a broader scale, international comparisons remain essential for validating measurement capabilities and ensuring global coherence, as emphasized in a recent overview of their critical role in the metrological infrastructure. This paper argues that the integration of rigorous uncertainty budgeting with coordinated international comparisons is indispensable for sustaining confidence in next-generation optical and photonic dimensional metrology.