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Towards a fiber-coupled picowatt cryogenic radiometer



Nathan A. Tomlin, John H. Lehman, Sae Woo Nam


A picowatt cryogenic radiometer (PCR) has been fabricated at the microscale level for electrical substitution optical fiber power measurements. The absorber, electrical heater, and thermometer are all on a micromachined membrane less than 1mm on a side. Initial measurements with input powers from 50 fW to 20 nW show a response inequivalence between electrical and optical power of 8%. A comparison of the response to electrical and optical input powers between 15 pW to 70 pW yields a repeatability better than {+or-} 0.3 % (k = 2). From our first optical tests, the system has a noise equivalent power of ≅5× 10-15 W∕ √Hz at 2 Hz, but simple changes to the measurement scheme should yield an NEP 2 orders of magnitude lower.
Applied Physics Letters


absolute cryogenic radiometer, picowatt, pW, transition-edge sensor, TES, ACR, radiometer


Tomlin, N. , Lehman, J. and Nam, S. (2012), Towards a fiber-coupled picowatt cryogenic radiometer, Applied Physics Letters, [online], (Accessed June 22, 2024)


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Created June 11, 2012, Updated February 19, 2017