Prober, Daniel E. | Search NASA

NASA NTRS2014

Monolayer Graphene Bolometer as a Sensitive Far-IR Detector

In this paper we give a detailed analysis of the expected sensitivity and operating conditions in the power detection mode of a hot-electron bolometer (HEB) made from a few micro m(sup 2) of monolayer graphene (MLG) flake which can be embedded into either a planar antenna or waveguide circuit via NbN (or NbTiN) superconducting contacts with critical temperature approx. 14 K. Recent data on the strength of the electron-phonon coupling are used in the present analysis and the contribution of the readout noise to the Noise Equivalent Power (NEP) is explicitly computed. The readout scheme utilizes Johnson Noise Thermometry (JNT) allowing for Frequency-Domain Multiplexing (FDM) using narrowband filter coupling of the HEBs. In general, the filter bandwidth and the summing amplifier noise have a significant effect on the overall system sensitivity.

noise thermometry↗

NASA NTRS2010

Development of the Nano-HEB Array for Low-Background Far-IR Applications

We present an overview of the recent progress made in the development of a far-IR array of ultrasensitive hot-electronnanobolometers (nano-HEB) made from thin titanium (Ti) films. We studied electrical noise, signal and noisebandwidth, single-photon detection, optical noise equivalent power (NEP), and a microwave SQUID (MSQUID) basedfrequency domain multiplexing (FDM) scheme. The obtained results demonstrate the very low electrical NEP down to1.5x10-(sup 2)? W/Hz(sup 1)/(sup 2) at 50 mK determined by the dominating phonon noise. The NEP increases with temperature as ~ T(sup 3)reaching ~ 10-(sup 1)? W/Hz(sup 1)/(sup 2) at the device critical temperature TC = 330-360 mK. Optical NEP = 8.6x10-(sup 1)? W/Hz(sup 1)/(sup 2) at 357mK and 1.4x10-(sup 1)? W/Hz(sup 1)/(sup 2) at 100 mK respectively, agree with thermal and electrical data. The optical couplingefficiency provided by a planar antenna was greater than 50%. Single 8-?m photons have been detected for the first timeusing a nano-HEB operating at 50-200 mK thus demonstrating a potential of these detectors for future photon-countingapplications in mid-IR and far-IR. In order to accommodate the relatively high detector speed (~ ?s at 300 mK, ~ 100 ?sat 100 mK), an MSQUID based FDM multiplexed readout with GHz carrier frequencies has been built. Both the readoutnoise ~ 2 pA/Hz(sup 1)/(sup 2) and the bandwidth > 150 kHz are suitable for nano-HEB detectors.

single-photon↗