TRANSFER OF MOMENTUM AND TORQUE FROM A LIGHT-BEAM TO A LIQUID

Refraction or absorption of light results in the force and torque, i.e ., transfer of momentum and angular momentum from light to the medium. In transversely inhomogeneous beams, the force per unit volume f may have curlf not equal 0 leading to flow or to nonthermal and nongravita tional convection in liquids. The force and the torque in scattering s ystems are as strong as in absorbing materials and may allow one to ca rry out experiments avoiding thermal effects. Nonlinear optical respon se of liquid crystals due to this convection is discussed.