A white-light interferometry scheme to measure wide-wavelength dispersion of thermo-optic coefficients of optical switch materials

This paper reports demonstration of a new simple white-light interferometry method for continuous dispersion curves of the thermo-optic (TO) coefficients of optical samples. Phase shifts of the interference spectra of the white-light interferometer output are measured by changing temperature of an optical sample located in the one of the interferometer arms. A continuous dispersion curve of the TO coefficient of the sample materials over the full wavelength coverage region of the white light beam is obtained from the phase shift information with the temperature change. This new method is tested with a fused silica glass material of well-known optical properties to prove its accuracy by comparing the measured results with its known TO coefficient values. This continuous dispersion information of the TO coefficients of new optical materials will be useful for fabrication of the WDM signal processing devices or functional devices in multi-wavelengths.