Observation of fs laser-induced heat dissipation in diamond bulk

Dynamics of refractive index variation in diamond crystal during and after its irradiation by fs laser pulses has been investigated by the pump–probe interferometric technique. It is found that, as well as the positive +Δn variation of refractive index determined by the Kerr effect and the negative −Δn resulting from bulk ionization, there is a positive +Δn determined by material heating. Analysis of experimental data and modeling allows us to visualize a laser heated volume, to trace its growth in time and to determine the temperature of material in the beam waist. The maximum observed temperature for intensity ≈3 × 1012 W cm−2 is estimated as 700 K. (letter)