Laser fabrication at submicron scale is experimentally demonstrated with the nonlinear optical switching effect of photochromism. The effect, which is a result of change in the optical properties of the photochromic material between the open-ring and closed-ring isomers during the photoisomerization, effectively reduces the laser beam size. The ultrafast response of the molecular photocyclization and cycloreversion reactions at a time scale of a few picoseconds ensures the instantaneous realization of the effect. Utilizing a photochromic film of cis-1,2-dicyano-1,2-bis(2,4,5-trimethyl-3-thienyl) ethane as the mask layer, laser processing of a silicon wafer demonstrated submicron scale feature size with improved surface quality as compared to the smallest features achievable using direct laser ablation without the photochromic film. (C) 2004 Elsevier B.V. All rights reserved.