VECTORIAL SPATIAL SOLITARY WAVES AND SELF INDUCED RESONANT CAVITIES

Three-dimensional self guided beams of transverse magnetic (TM) type in saturable self focusing media are examined. Self guidance in saturable nonlinear media is found possible in an infinite set of TM modes provided that the maximum saturable nonlinear refractive index n(sat) is greater than the linear refractive index n0 of the medium and the beam effective refractive index n(eff) is limited to n0 < n(eff) < n(sat). The similarities and differences of self trapped TM beams in the Kerr law nonlinearity and saturable nonlinearity are compared. Self induced resonant cavities are also investigated. The resonant condition of a laser cavity or resonator operating at high intensity is shown to depend on the amount of energy stored in the cavity, in contrast to a linear cavity the resonant condition of which is determined by the cavity geometric structure only. The results presented should be useful for explaining and analysing operation of some laser cavities in which the transverse cavity fields extend less or much less than the cavity active media.