Temperature dependence of the thermo-optic coefficient in crystalline silicon between room temperature and 550 K at the wavelength of 1523 nm

The temperature dependence of the thermo-optic coefficient for crystalline silicon has been measured in the temperature range between room temperature and 550 K at the wavelength of 1523 nm by means of an interferometric tech nique. This technique, which requires a very simple experimental setup, is based on the observation of the fringe pattern produced by temperature chan ges in a Fabry-Perot resonator. Measurement results indicate that the therm o-optic coefficient is independent on the sample doping and crystal plane o rientation. The experimental data appear to be in agreement with the few va lues reported to date at this important wavelength. The temperature depende nce of the excitonic band gap is also calculated by fitting these data with a recently introduced model of partial derivative n/partial derivative T. (C) 1999 American Institute of Physics. [S0003-6951(99)02622-4].