Photon Counting OTDR : Advantages and Limitations

TL;DR

This paper explores photon counting OTDR technology, highlighting its potential to significantly improve dynamic range and resolution over traditional OTDRs, while discussing operational modes and current limitations.

Contribution

It provides a comprehensive analysis of nu-OTDR operation, demonstrating its advantages in dynamic range and resolution, and discusses optimal operational modes and limitations.

Findings

Potential to outperform conventional OTDR by 10 dB in dynamic range

Achieves 20 times better 2-point resolution

Limited improvement in dead zone performance without additional measures

Abstract

We give detailed insight into photon counting OTDR (nu-OTDR) operation, ranging from Geiger mode operation of avalanche photodiodes (APD), analysis of different APD bias schemes, to the discussion of OTDR perspectives. Our results demonstrate that an InGaAs/InP APD based nu-OTDR has the potential of outperforming the dynamic range of a conventional state-of-the-art OTDR by 10 dB as well as the 2-point resolution by a factor of 20. Considering the trace acquisition speed of nu-OTDRs, we find that a combination of rapid gating for high photon flux and free running mode for low photon flux is the most efficient solution. Concerning dead zones, our results are less promising. Without additional measures, e.g. an optical shutter, the photon counting approach is not competitive.