Time-dependence of the transmission matrix of a specialty few-mode fiber

TL;DR

This paper presents a method for time-resolved measurement of the full transmission matrix of a specialty few-mode fiber, revealing phase drift characteristics over two days and proposing an empirical model to describe these drifts.

Contribution

It introduces a novel measurement technique for the fiber's transmission matrix and models its time-dependent drift with a single-parameter empirical model.

Findings

TM drifts are mainly phase variations

Drifts can be modeled with a single parameter

Method isolates fiber TM from optical misalignments

Abstract

We report a time-resolved measurement of the full transmission matrix (TM) of a short length of specialty annular-core few-mode fiber which guides 10 vector modes. We show how our method can isolate the fiber TM from misalignment contributions from optics upstream and downstream of the fiber. From measurements spanning two days we extract the drift of the fiber TM. We show that drifts in the TM elements are mostly described as correlated phase variations rather than amplitude variations. We show that an empirical model of the fiber TM parametrized in one parameter can successfully account for the drift.