CARRIER-INDUCED CHANGE DUE TO DOPING IN REFRACTIVE-INDEX OF INP - MEASUREMENTS AT 1.3 AND 1.5 MU-M

Accurate measurements of the InP refractive index as a function of fre e-carrier doping are reported at 1.3 and 1.5 mu m, the two strategic w avelengths for optical communications. A total of 21 samples with diff erent N- and P-doping levels have been measured using a novel and simp lified grating-coupling technique. Ln contrast to the conventional met hod, this only involves the use of a directly etched diffraction grati ng on the sample surface, thereby avoiding the necessity of a specific guiding layer. The measured index, in agreement with earlier predicti ons, decreases by more than 0.05 when the N doping is increased from b elow 10(15) to about 10(19) electrons per cubic centimeter, This effec t, however, is much less pronounced with P doping than with N doping. (C) 1996 American Institute of Physics.