Small signal analysis for analogue optical links with arbitrary optical transfer function - Electronics Letters

Introduction: The conversion matrix [1–3], connecting the optical intensity and phase variations at the output of an optical device with their corresponding input values, has been found useful in analysing laser and amplifier noise in analogue optical links and for computing the RF transfer function of various hybrid RF=optical systems. Previous works assumed the optical devices to be characterised by an all-phase transfer function [1–3], where the optical phase, was approximated by a finite order Taylor expansion around the optical centre frequency. However, present day optical devices have more complex transfer functions, including both phase and amplitude variations, at higher RF frequencies (millimetre waves) and with ever-wider RF bandwidths [4], requiring a more generalised matrix. This Letter derives such a matrix, valid for small signal modulation.