Enhanced Bandwidth in Radiation Sensors Operating at the Fundamental Temperature Fluctuation Noise Limit.
basic_science · Level V
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- Record sourced from PubMed, PMID 40999943.
- Also identified by DOI 10.1021/acs.nanolett.5c03415.
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Abstract
Temperature-based radiation detectors are essential for long-wavelength detection, but they suffer from important bandwidth limitations. Their responsivity and, hence, their noise equivalent power (NEP) typically degrade at frequencies exceeding their characteristic thermal response time cutoff (τ<sub>th</sub>), i.e., at ω > τ<sub>th</sub><sup>-1</sup>. We show that this bandwidth limitation can be broken when a sensor operates at its fundamental temperature fluctuation noise limit. The key enabler of this demonstration is a nanomechanical sensor in which frequency stability is limited by fundamental temperature fluctuations over an unprecedentedly large bandwidth of 54 Hz. In this range, the sensor performance remains within a factor 3 of its peak detectivity (<i>D</i><sub><i>T</i></sub><sup>*</sup> = 7.4 × 10<sup>9</sup> cm Hz<sup>1/2</sup> W<sup>-1</sup>) even though the thermal cutoff frequency is 30 times lower (i.e., 1/2πτ<sub>th</sub> = 1.8 Hz). We also derive expressions predicting this bandwidth enhancement for nanomechanical resonator-based sensors within a closed-loop frequency tracking scheme.