SELF-FOCUSING AND SELF-TRAPPING IN SMECTIC-A LIQUID-CRYSTAL

The self-focusing of a laser beam due to the Kerr nonlinearity caused by layer deformations in a smectic A liquid crystal (SmA) is considere d. It is shown that for a sufficiently high intensity the beam undergo es self-trapping forming a spatial soliton. The same mechanism is resp onsible for the self-trapping of a surface-guided light wave at the in terface of a linear medium and SmA. Numerical estimations show that th e new Kerr nonlinearity is approximately 10 times greater than a nonli nearity caused by bulk compression. Self-trapping effect may be observ ed in smectic A liquid crystal samples of a thickness of 0.01 cm and a t a light beam power of an order of magnitude of 0.002 MW.