Avalanche Photo-Detection for High Data Rate Applications

TL;DR

This paper investigates the operational limits of avalanche photodiodes (APDs) for high data rate photon detection, analyzing their linearity, non-linear response, and photon-number resolution capabilities using time multiplexed detectors.

Contribution

It introduces a method to characterize APD linearity at high data rates and demonstrates how TMDs extend photon-number resolution, improving accuracy in photon statistics measurement.

Findings

APDs exhibit limited linearity at high repetition rates due to dead time.

Non-linear response occurs at higher photon numbers from multiphoton events.

Time multiplexed detectors improve photon-number resolution and linearity range.

Abstract

Avalanche photo detection is commonly used in applications which require single photon sensitivity. We examine the limits of using avalanche photo diodes (APD) for characterising photon statistics at high data rates. To identify the regime of linear APD operation we employ a ps-pulsed diode laser with variable repetition rates between 0.5MHz and 80MHz. We modify the mean optical power of the coherent pulses by applying different levels of well-calibrated attenuation. The linearity at high repetition rates is limited by the APD dead time and a non-linear response arises at higher photon-numbers due to multiphoton events. Assuming Poissonian input light statistics we ascertain the effective mean photon-number of the incident light with high accuracy. Time multiplexed detectors (TMD) allow to accomplish photon- number resolution by photon chopping. This detection setup extends the linear response function to higher photon-numbers and statistical methods may be used to compensate for non-linearity. We investigated this effect, compare it to the single APD case and show the validity of the convolution treatment in the TMD data analysis.