Characterization of XGM and XPM in a SOA-MZI using a linear frequency resolved gating technique

Abstract

Semiconductor Optical Amplifiers (SOAs) are of considerable interest as nonlinear optical processing devices, since they can facilitate such operations as signal regeneration and wavelength conversion. All optical processing of signals in SOAs usually employs either cross-gain modulation (XGM) or cross-phase modulation (XPM). In the latter case, to convert phase changes to intensity variations, it is common to use integrated SOA Mach-Zehnder interferometers (SOA-MZIs). As signal repetition rates approach the operating bandwidth of the SOA devices, precise knowledge of their response in both intensity and phase becomes ever more crucial. The usual approach to the phase-sensitive characterisation of fast optical devices involves the use of interferometric set-ups [1], which can be quite involving and prone to environmental instabilities. In this paper, and in order to aid the optimisation of these versatile devices we present a study of SOA response behaviour using a linear frequency resolved gating technique (L-FROG). The L-FROG allows the phase and intensity of signals to be characterized using off-the-shelf all-fiberised equipment in a simple non-interferometric set-up. Using a SOA-MZI in a pump-probe configuration, we investigate both the XGM and XPM response to ps-long pump signals. Since intraband effects such as carrier heating and spectral hole burning, which facilitate high-speed switching, are dependent on the power of the incoming signals, we focus our studies on the variation of the SOA response to the input power. Through this study we hope to provide a better understanding of the nonlinear behaviour of SOA devices, and additionally prove the applicability of LFROG techniques for the complete characterisation of fast optical device response behaviour.

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Identifiers

ORCID for David J. Richardson: orcid.org/0000-0002-7751-1058

ORCID for Periklis Petropoulos: orcid.org/0000-0002-1576-8034

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