Measurement of the facet modal reflectivity spectrum in high quality semiconductor traveling wave amplifiers

Abstract

We demonstrate that the Hakki-Paoli technique, commonly used for measuring single pass gain in semiconductor lasers, can be modified to measure facet modal reflectivity down to 10/sup -6/ in semiconductor laser amplifiers. We also introduce a new technique based on Fourier and Hilbert transformations of the spontaneous emission spectrum (the SET method) which enhances the signal-to-noise ratio and permits modal reflectivity measurements down to 10/sup -1/.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>