Abstract

Many new applications using nonlinear optics have recently been realised by exploiting the very high nonlinearities of Chalcogen-based optical fibres [1]. The Two-Photon Absorption (TPA) coefficient for As₂Se₃ Chalogenide-glass fibre is β=0.25cm/GW at 1550nm, which is close to a comnonly-used nonlinear material like Silicon (β=0.8cm/GW). In this work we build upon a methodology previously suggested in [2] that employs time-averaged nonlinear detection to measure the duty cycle (and thus the pulse duration) of a signal under test (SUT). The technique in [2] employed TPA in Silicon APDs, while in our technique the TPA in the Chalcogenide fibre fonns the basis of the nonlinear detection. Our technique has the key advantage of being fibre-based that allows for a long interaction length, and therefore more nonlinear absorption, which allows for greater sensitivity in the nonlinear detection measurements.

© 2007 IEEE