The role of electrostriction in the generation of acoustic waves by optical forces in water

We present semi-analytical solutions describing the spatiotemporal distributions of temperature and pressure inside low-absorbing dielectrics excited by tightly focused laser beams. These solutions are compared to measurements in water associated with variations of the local refractive index due to acoustic waves generated by electrostriction, heat deposition, and the Kerr effect at different temperatures. The experimental results exhibited an excellent agreement with the modeling predictions, with electrostriction being the dominant transient effect in the acoustic wave generation. Measurements at 4.0∘C show that the thermoelastic contribution to the optical signal is significantly reduced due to the low thermal expansion coefficient of water at this temperature.