Abstract
We have previously presented work describing a new optical fibre-coupled cryogenic primary standard facility at NIST. The new radiometer replaced a liquid helium system as the primary standard for the traceable dissemination of the power responsivity of fibre-coupled visible and near-infrared detectors [1]. The facility has been upgraded and now uses polarisation maintaining (PM) fibre throughout, from the Fabry-Pérot fibre-coupled laser diode sources, through the variable optical attenuators with integral shutters and PM fibre beam-splitters [2]. The system is used at wavelengths of 850 nm, 1310 nm and 1550 nm, with an expanded uncertainty of 0.1 %.
This presentation will illustrate how we assessed the main contributors to the uncertainty budget and thus were able to improve the overall uncertainty from 0.4 % to 0.1 %.
We have measured the temperature dependent change of the Fresnel reflection loss and Rayleigh backscatter of PM single-mode fibre as it was cooled to 5 K. This change in Fresnel reflection accounts for a small 0.03 % correction to the room temperature beam-splitter ratio measurement between the radiometer and the device under test (DUT). We used an in-situ beam-splitter measurement technique to measure the Fresnel reflection and we confirmed the results at 1550 nm with an optical frequency domain reflectometer measurement.
Passive optical components such as fibre beam-splitters and couplers exhibit polarisation dependent loss (PDL), whereby the output signal of the device varies as a function of the input polarisation state. In our setup this affects the room temperature beam-splitter ratio between radiometer and DUT. The temperature dependence of the PDL was evaluated, using the Mueller matrix method, for fused biconical and planar polarisation maintaining fibre beam-splitters at 1310 nm and 1550 nm over the range 10 ºC to 40 ºC. The uncertainty in determining this ratio will be discussed during the presentation.
We have also assessed the impact that the temporal and spectral modal stability of the Fabry-Pérot laser diode sources have on the power responsivity of the DUT. The wavelength uncertainty that arises is incorporated into the uncertainty budget.
This work improves and further assures the performance of our optical fibre-coupled cryogenic radiometer facility.
1. M.G. White, Z.E. Ruiz, C.S. Yung, I. Vayshenker, N.A. Tomlin, M.S. Stephens, and J.H. Lehman, “Cryogenic primary standard for optical fibre power measurement”, Metrologia 55(5), 706-715 2018
2. M.G. White, E. Baumann, I. Vayshenker, Z.E. Ruiz, M.S. Stephens, M. Smid and J.H. Lehman, “The nature of fibre coupled detector responsivity measurements at 0.1 % using a primary standard”, Submitted Opt. Express, Feb. 2020
Detector Responsibity by Fibre Coupled Cryogenic Primary Standard at 0.1%
We have previously presented work describing a new optical fibre-coupled cryogenic primary standard facility at NIST. The new radiometer replaced a liquid helium system as the primary standard for the traceable dissemination of the power responsivity of fibre-coupled visible and near-infrared detectors [1]. The facility has been upgraded and now uses polarisation maintaining (PM) fibre throughout, from the Fabry-Pérot fibre-coupled laser diode sources, through the variable optical attenuators with integral shutters and PM fibre beam-splitters [2]. The system is used at wavelengths of 850 nm, 1310 nm and 1550 nm, with an expanded uncertainty of 0.1 %.
This presentation will illustrate how we assessed the main contributors to the uncertainty budget and thus were able to improve the overall uncertainty from 0.4 % to 0.1 %.
We have measured the temperature dependent change of the Fresnel reflection loss and Rayleigh backscatter of PM single-mode fibre as it was cooled to 5 K. This change in Fresnel reflection accounts for a small 0.03 % correction to the room temperature beam-splitter ratio measurement between the radiometer and the device under test (DUT). We used an in-situ beam-splitter measurement technique to measure the Fresnel reflection and we confirmed the results at 1550 nm with an optical frequency domain reflectometer measurement.
Passive optical components such as fibre beam-splitters and couplers exhibit polarisation dependent loss (PDL), whereby the output signal of the device varies as a function of the input polarisation state. In our setup this affects the room temperature beam-splitter ratio between radiometer and DUT. The temperature dependence of the PDL was evaluated, using the Mueller matrix method, for fused biconical and planar polarisation maintaining fibre beam-splitters at 1310 nm and 1550 nm over the range 10 ºC to 40 ºC. The uncertainty in determining this ratio will be discussed during the presentation.
We have also assessed the impact that the temporal and spectral modal stability of the Fabry-Pérot laser diode sources have on the power responsivity of the DUT. The wavelength uncertainty that arises is incorporated into the uncertainty budget.
This work improves and further assures the performance of our optical fibre-coupled cryogenic radiometer facility.
1. M.G. White, Z.E. Ruiz, C.S. Yung, I. Vayshenker, N.A. Tomlin, M.S. Stephens, and J.H. Lehman, “Cryogenic primary standard for optical fibre power measurement”, Metrologia 55(5), 706-715 2018
2. M.G. White, E. Baumann, I. Vayshenker, Z.E. Ruiz, M.S. Stephens, M. Smid and J.H. Lehman, “The nature of fibre coupled detector responsivity measurements at 0.1 % using a primary standard”, Submitted Opt. Express, Feb. 2020