Second generation room-temperature dual-mode photodiodes with record-low uncertainties

Le résumé fourni par la source

Abstract The dual-mode method enables self-calibration of photodiodes by combining a photocurrent measurement with an electrical-substitution measurement of the absorbed optical power. Recent developments have focused on reducing thermal non-equivalence between optical and electrical heating, which limits accuracy through unwanted dependencies on beam position, power level and operating temperature. In this work, we present a new generation of dual-mode modules designed to improve thermal symmetry through a backside resistive heater, a redesigned thermal conduction path and an assembly approach optimized for manufacturability. The new design also facilitates the implementation of the dual-mode method with photodiodes based on materials other than silicon. We characterize the modules experimentally and with finite-element simulations. The measurements show a substantial reduction in position-dependent non-equivalence, from 230 ppm mm −1 for the previous generation to no significant dependency for the new generation. The measurements also reveal a clearly measurable dependence on optical power and relative temperature. These two effects are quantified and used to correct the apparent internal quantum deficiency (IQD). The resulting corrected IQD when measuring at the center of the diode with 748 µ W optical power is −73 ppm ± 34 ppm ( k = 1), consistent with simulations and representing the lowest uncertainty achieved with room-temperature dual-mode photodiodes to date. Remaining discrepancies between simulations and measurements highlight the need for improved thermal modeling, particularly regarding radiative coupling. The results demonstrate that the revised module design provides a robust pathway toward compact self-calibrating photodiodes with uncertainties equivalent to those of cryogenic radiometers.

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