Abstract

The linewidth enhancement factor, b, is an important parameter in semiconductor optoelectronic devices. It describes the coupling of carrier induced variations of the real and imaginary parts of the susceptibility. It can be defined as b = -2 k(dn/dN)/(dg/dN) where k is the vacuum wave-vector, n the index of refraction, g the gain, and N the carrier density. The experiment was performed on an index guided InGaAsP/InP buried heterostructure amplifier. We have independently measured the phase change (change in index of refraction) and the gain for different injected currents and different wavelengths. The value of the phase change was determined by the fringe shift in a Mach–Zehnder interferometer. We have optically probed the amplifier using a weak continuous wave probe from a NaCl:OH color-center laser in the wavelength range between 1.50 and 1.58 mm. Initial results will be reported for the b factor as a function of parameters such as wavelength and injected current.

© 1990 Optical Society of America