Predictable quantum efficient detector for low optical flux measurements

Abstract

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.

Characterization of predictable quantum efficient detector in terms of optical non-linearity in the visible to near-infrared range

“…Another advantage of using the quantum detector such as Si PDs in determining the absolute radiant flux is that it helps us to extend measurable flux range much greater than six orders of magnitude. The measured photocurrent for the PQED was tens of nano-amperes in the optical measurement with lightemitted-diodes [17], miliamperes in the absolute radiant flux measurement with stabilized lasers [12], and pW levels in the absolute radiant flux measurement with a stabilized laser at a cryogenic temperature [19]. Thus, the linearity of Si PD with respect to the incident radiant flux at various wavelengths is a fundamental element to determine the absolute radiant flux in a range greater than six orders of magnitude, because it would show a non-linear response at a certain radiant flux level with a decrease or increase in responsivity [20][21][22].…”

Linearity and nonlinearity of silicon photodiodes for accurate absolute optical flux measurements: a review

“…Based on their characteristics, various studies have examined the possibility of using commercial Si PDs as standard detectors of absolute optical flux [9][10][11][12][13]. By utilizing specially designed Si PDs, a predictable quantum efficient detector was also developed [14][15][16][17][18], and its feasibility as a primary standard was demonstrated [19][20][21][22]. Nevertheless, the true capability of an optical detector constructed using Si PDs as a primary standard is still a hot research topic [23][24][25].…”

Characterization of predictable quantum efficient detector at 488 nm and 785 nm wavelengths with an order of magnitude change of incident optical power

“…Two induced junction photodiodes of the PQED are aligned in a wedged trap configuration providing a primary standard detector for visible wavelengths [3,4,14]. In addition to calibration of working standard detectors, the PQED can be used in various applications in photometry [15] and in measurements of low optical power when operated at liquid nitrogen temperatures [16,17].…”