3-DIMENSIONAL 2ND-HARMONIC GENERATION IMAGING WITH FEMTOSECOND LASER-PULSES

A three-dimensional reflectance scanning optical microscope based on t he nonlinear optical phenomenon of second-harmonic generation is prese nted. A mode-locked Ti:sapphire laser producing <90-fs pulses at simil ar to 790 nm was used, and the images were constructed by scanning of an object, which possessed local second-order nonlinearity, relative t o a focused spot from the laser. The second-harmonic light at similar to 395 nm generated by the specimen was separated from the fundamental beam by use of dichroic and interference filters and was detected by a photodiode. The technique was then used to characterize the distribu tion of second-order nonlinearity and microstructure of the nonlinear material lithium triborate. (C) 1998 Optical Society of America.