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We report a measurement of the quantum efficiency for a surface plasma wave (SPW)-coupled InAs/In_0.15Ga_0.85As/GaAs dots-in-a-well (Dwell) quantum dot infrared photodetector (QDIP) having a single-color response at ∼10 µm. A gold film perforated with a square array of complex, non-circular apertures is employed to manipulate the near-fields of the fundamental SPW. The quantum efficiency is quantitatively divided into absorption efficiency strongly enhanced by the SPW, and collection efficiency mostly independent of it. In the absorption efficiency, the evanescent near-fields of the fundamental SPW critically enhances QDIP performance but undergoes the attenuation by the absorption in the Dwell that ultimately limits the quantum efficiency. For the highest quantum efficiency available with plasmonic coupling, an optimal overlap between Dwell and SPW near-fields is required. Based on experiment and simulation, the upper limit of the plasmonic enhancement in quantum efficiency for the present device is addressed.

 

A bstract Charged-lepton-flavor-violation is predicted in several new physics scenarios. We update the analysis of τ lepton decays into a light charged lepton ( ℓ = e ± or μ ± ) and a vector meson ( V 0 = ρ 0 , ϕ , ω , K *0 , or $$ \overline{K} $$ K ¯ *0 ) using 980 fb − 1 of data collected with the Belle detector at the KEKB collider. No significant excess of such signal events is observed, and thus 90% credibility level upper limits are set on the τ → ℓV 0 branching fractions in the range of (1.7–4 . 3) × 10 − 8 . These limits are improved by 30% on average from the previous results.