Determination of the optical constants of a thin film from transmittance measurements of a single film thickness

A subtractive Kramers-Kronig method is presented for obtaining the optical constants, n and k, of a uniform absorbing film on a substrate using the transmittance spectrum of a single film thickness. We give the results of tests on the reliability of our method, demonstrate the usefulness of the method when only transmittance data are available, and give examples of thin films whose optical constants depend on their thickness.