Carrier-induced change due to doping in refractive index of InP: Measurements at 1.3 and 1.5 μm

Abstract

Accurate measurements of the InP refractive index as a function of free-carrier doping are reported at 1.3 and 1.5 μm, the two strategic wavelengths for optical communications. A total of 21 samples with different N- and P-doping levels have been measured using a novel and simplified grating-coupling technique. In contrast to the conventional method, this only involves the use of a directly etched diffraction grating on the sample surface, thereby avoiding the necessity of a specific guiding layer. The measured index, in agreement with earlier predictions, decreases by more than 0.05 when the N doping is increased from below 1015 to about 1019 electrons per cubic centimeter. This effect, however, is much less pronounced with P doping than with N doping. © 1996 American Institute of Physics.