Investigation of the carrier density dependence on the confinement factor in a bulk semiconductor optical amplifier with a ridge waveguide

In this work we demonstrate that the confinement factor value can strongly depend on the carrier density in long bulk semiconductor optical amplifiers with a ridge waveguide (RW-SOAs). Theoretically we shown that a 1.5 dBm input beam increases the confinement factor in such a manner that the investigated 1.5 mm length RW-SOA allows an acceptable guiding of a frequently neglected TE01 mode. In order to avoid heavy calculations, a simple expression relating the confinement factor with the carrier density is derived from theoretical results obtained from a rigorous analysis. Finally, an experimental method allowing a qualitative visualization of the confinement factor modification provoked by an input power fluctuation and therefore by a carrier density variation, is presented. (C) 2003 Elsevier Science B.V. All rights reserved.