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Q: Quantenoptik und Photonik

Q 76: Poster Quantenkommunikation

Q 76.2: Poster

Donnerstag, 16. März 2006, 16:30–18:30, Labsaal

Avalanche photodetection for applications with high repetition rates — •Hendrik Coldenstrodt and Christine Silberhorn — Max-Planck-Nachwuchsgruppe, Günther-Scharowsky Str.1 / Bau 24, 91058 Erlangen

Quantum communication requires single photon detection, implying the use of avalanche photo diodes (APDs). If one wants to operate APDs at the highest feasible bit rates in cw-operation, a correction factor is typically taken into account for increasing count rates. An other interesting field, where effective high repetition rates have to be considered, is the use of APDs in time multiplexing detectors for photon number resolution[1]. Thus an essential task is to determine the properties of the correction factor and a threshold frequency below which the APDs yield reliable data for pulsed systems.

We investigated the properties of APDs with a ps-pulsed diode laser at 805nm and repetition rates between 0.5MHz and 80MHz. Different levels of attenuation were applied, such that we were able to identify the regime of linear APD operation, in dependence of the repetition frequency and the mean optical power. The linearity at high repetition rates is limited by the APD dead time and a non-linearity arises at higher photon-numbers due to multiphoton events. Assuming Poissonian input light statistics we ascertained the mean photon-number of the incident light with high accuracy. The results are compared to the statistics obtained using an advanced time multiplexing detector, allowing for data rates up to 1MHz.

[1] D. Achilles et al. J. Mod. Opt. 51, 1499 (2004)