Position Dependence of High Efficiency Single Photon Detectors: A Route to Better Understanding of Transition Edge Sensors

Undergraduate Honors Thesis

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Citeable URL: https://scholar.colorado.edu/concern/undergraduate_honors_theses/6108vb69p

Abstract

Superconducting tungsten in an optical stack has demonstrated near unity absorption at 1550 nm. High detection efficiency and a low operational temperature (0.16 K) provide energy resolution sufficient for single-photon counting. The spatial dependence of the device response has been measured, revealing dependencies in detected photon number, energy resolution, and thermalization that result from small misalignment from the device center. Additional measurements at 785 nm demonstrating the position-dependent behavior of this Transition Edge Sensor (TES) at a suboptimal wavelength are also reported. Single photon measurements at 785 nm and higher photon energy have demonstrated a characteristic "half photon" anomaly that may be due to one of several proposed interactions. Preliminary results of the position dependence of this phenomenon supports the hypothesis of thermal absorptions off-detector in the substrate.

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