Perturbation of the Refractive Index of Absorbing Media by a Pulsed Laser Beam

The effects on the index of refraction of various media due to energy absorbed from a long‐pulsed and a Q‐switched Nd‐doped glass laser are investigated with a Mach‐Zehnder interferometer. These effects are reasonably well predicted from the temperature coefficient of the index and the heat capacity of the media. Sonic waves generated by the Q‐switched laser are observed in cases for which either heating or electro‐striction is dominant.