Predictable quantum efficient detector for low optical flux measurements

Research output: Contribution to journalConference articleScientificpeer-review


Research units

  • VTT MIKES Metrology


The predictable quantum efficient detector (PQED) is a primary standard of optical power, which utilizes two custom-made induced-junction photodiodes that are mounted in a wedged trap configuration for the reduction of reflectance losses. PQED photodiodes of p-type and n-type were characterized for their dark current dependence on reverse bias voltage at room temperature. As simulations predict that the dark current will decrease exponentially with temperature, the temperature dependence of dark current for the n-type photodiodes was also measured. Two n-type induced-junction photodiodes were assembled inside a liquid nitrogen cryostat. The results from the dark current measurements indicate that the cooled n-type photodiodes are suitable for measuring optical fluxes in the few photon regime. A photon flux of approximately 7,000,000 photons per second was measured using the PQED at a cryogenic temperature with a relative standard uncertainty of 0.15%. The results support the utilization of the PQED as a primary standard of optical power in single and few photon applications.


Original languageEnglish
Number of pages5
Publication statusPublished - 1 Feb 2020
MoE publication typeA4 Article in a conference publication
EventJapan-Finland Joint Symposium on Optics in Engineering - Aalto University, Espoo, Finland
Duration: 26 Aug 201930 Aug 2019
Conference number: 13

    Research areas

  • Dark current, Induced junction, Low optical flux, Silicon photodetector

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