Bergé, LBang, OleKrolikowski, Wieslaw2009-10-222010-12-202009-10-222010-12-20Physical Review Letters 84.15 (2000): 3302-33050031-90071079-7114http://hdl.handle.net/10440/957http://digitalcollections.anu.edu.au/handle/10440/957Four-wave mixing and walk-off between two optical beams are investigated for focusing Kerr media. It is shown that four-wave mixing reinforces the self-focusing of mutually trapped waves by lowering their power threshold for collapse, only when their phase mismatch is small. On the contrary, walk-off inhibits the collapse by detrapping the beams, whose partial centroids experience nonlinear oscillations.4 pageshttp://www.sherpa.ac.uk/romeo/index.php "Author can archive pre-print (ie pre-refereeing) … post-print (ie final draft post-refereeing) … [and] publisher's version/PDF. Link to publisher version … [and] Copyright notice required. Publisher's version/PDF can be used on … employers web site." - from SHERPA/RoMEO site (as at 25/02/10). ©2000 The American Physical Society200010.1103/PhysRevLett.84.33022015-12-12