Use of the Predictable Quantum Efficient Detector with Light Sources of Uncontrolled State of Polarization

Abstract

Analysis of the reflectance losses of the Predictable Quantum Efficient Detector (PQED) operated at room temperature is presented. An efficient method of using the ratio of photocurrents from the two photodiodes of the PQED is developed to determine the reflectance losses without direct measurement of the reflectance for an unknown state of polarization of the incident light. A detailed analysis is presented to estimate the associated reflectance losses for detectors with either seven or nine internal reflections. For the seven-reflection PQED, the relative standard uncertainty component of spectral responsivity due to reflectance loss correction can be reduced typically below 100 ppm with the photocurrent ratio measurement whereas for the nine‑reflection PQED the uncertainties remain below 20 ppm in the wavelength range from 400 nm to 900 nm with an uncontrolled polarization state of the incident light.