Date of Award

Winter 1997

Document Type


Degree Name

Doctor of Philosophy (PhD)


Electrical & Computer Engineering

Committee Director

Sacharia Albin

Committee Member

John B. Cooper

Committee Member

Armin N. Dharamsi

Committee Member

Linda L. Vahala


The Kramers-Kronig relations couple the real and imaginary part of the dielectric constant of a medium, namely the refractive index n(ω) and the extinction coefficient κ(ω). Changes in n(ω) due to normal and anomalous dispersion (Kramers-Kronig effect) are investigated for the first time using fiber optic couplers and tapers. Kramers-Kronig effect is induced by evanescent wave absorption in these devices. Couplers and tapers have oscillatory spectral outputs that are highly sensitive to the refractive index of the surrounding medium. Theoretical modeling of the Kramers-Kronig effect on couplers and tapers shows two distinct effects. First, the spectral outputs of these devices show a decrease in intensity due to evanescent wave absorption. Second, the spectral maxima and minima are shifted in wavelength due to Kramers-Kronig effect. Experimental studies clearly demonstrate Kramers-Kronig anomalous dispersion on fiber optic couplers and tapers. These devices are shown to be useful as chemical sensors.