title: Towards a fiber-coupled picowatt cryogenic radiometer.
abstract: 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 1 mm 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 ±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.
authors: National Institute of Standards and Technology, 325 Broadway, Boulder, Colorado 80305, USA. ntomlin@boulder.nist.gov
authors: N A
authors: NA
authors: Tomlin
authors: J H
authors: JH
authors: Lehman
authors: S
authors: S
authors: Nam