Low optical power reference detector implemented in the validation of two independent techniques for calibrating photon-counting detectors

Abstract

We introduce a technique for measuring detection efficiency that is traceable to the primary standard, the cryogenic radiometer, through a reference silicon photodiode trap detector. The trap detector, used in conjunction with a switched integrator amplifier, can measure signals down to the 0.1 pW (3 x 10⁵ photons second-1) level with 0.1% uncertainty in a total integration time of 300 seconds. This provides a convenient calibration standard for measurements at these levels across the optical spectrum (UV - near IR). A second technique is also described, based on correlated photons produced via parametric down-conversion. This can be used to directly measure detection efficiency in the photon counting regime, and provides a route for expanding the formulation of the candela in terms of photon flux to enable it to address the needs of emerging quantum optical technologies and applications. The two independent techniques were cross-validated by a comparison carried out at 702.2 nm, which showed agreement to within 0.2%.

Absolute calibration of a charge-coupled device camera with twin beams

“…Development of dedicated methods for absolute calibration of detectors in this context is therefore necessary, as it is widely recognised inside the radiometric community [8]. Some specific activities in this context are already on-going [9, 10], in particular related to the calibration of single-photon detectors exploiting the Klyshko's twinphoton technique [11][12][13][14][15][16][17][18] and its developments [19][20][21][22][23][24][25].…”

“…Development of dedicated methods for absolute calibration of detectors in this context is therefore necessary, as it is widely recognised inside the radiometric community [8]. Some specific activities in this context are already on-going [9, 10], in particular related to the calibration of single-photon detectors exploiting the Klyshko's twinphoton technique [11][12][13][14][15][16][17][18] and its developments [19][20][21][22][23][24][25].In particular, demand for precise calibration of detectors both in mesoscopic light regime it is relevant not only from the point of view of the development of quantum technologies, but also for establishing a connection between the light intensity level typical of classical radiometric measurements and the quantum radiometry operating at single-photon level [8, 9]. Quantum correlations in twin beams offer an opportunity for reaching this goal, as discussed in [26][27][28][29].…”

New detection systems for UV solar reference scanning spectroradiometers

“…Among the advantages of such approach is that once the value of C is calibrated, with typical uncertainty better than 100ppm, it is possible, measuring the integration time t, to know the current to voltage conversion factor up to 10 12 with the same low uncertainty given for C. A microcontroller-driven SIA has been developed by the Czech Metrology Institute which offers up to 7 order of magnitude of dynamic range and integration time generated on board that can be set by a controlling PC. The SIA has been successfully used in conjunction with a silicon trap detector for very low flux measurements at few hundred fW level [6] and has been shown to be linear (better than 10 -4 ) from 40 pW to 400 µW [4]. In order to further extend the sensitivity of the SIA-based detection system to lower power levels a small area/low dark current silicon detector has been selected (Hamamatsu 1227 33BQ).…”

“…Reference measurement systems for UV solar spectra such as QASUME are based on scanning double monochromator which offers stray light rejection as high as 10 6 and wavelength scale accuracy better than 0.05 nm [1]. The negligible stray light level at the output of the double monochromator is reached at the expenses of the low optical radiation output power that can be well below pW level for the sun spectrum in the UVB region.…”

Measuring absolute spectral radiance using an erbium-doped fiber amplifier

“…Recent advancements in the field of quantum optics and single-photon detectors has motivated work on accurate measurements at low powers [6,7], and their comparison with classical cryogenic radiometers [8,9].…”