Mg. Xu et al., Near band-edge field-dependent absorption coefficient and refractive indexdetermined by photocurrent and transmittance measurements, APPL OPTICS, 38(24), 1999, pp. 5127-5132
A technique is proposed for the extraction of precise values of field-depen
dent absorption coefficient alpha and refractive index n from photocurrent
and transmittance measurements of optical modulator structures. The techniq
ue uses approximate results of alpha and n extracted from a simplified devi
ce as the initial input into an iterative procedure that utilizes the consi
stency between alpha and n to obtain successively better estimates of these
parameters. The technique was applied to results that were measured experi
mentally, and we verified the accuracy by using synthetic data. Errors caus
ed by measurement inaccuracy are also investigated. It is shown that the ab
sorption coefficient has a modest sensitivity whereas the refractive index
is insensitive to these errors. (C) 1999 Optical Society of America. OCIS c
odes: 120.4530, 230.5590, 230.2090, 230.4110, 190.5970, 310.6860.