A method for preparing planar light waveguide by using ultra-short laser pulses includes such steps as using low-aperture (N.A. is less than 0.3) microscope to focus the ultra-short laser pulses in a dielectric sample, generating non-linear optical effects by the mutual action between laser pulse and dielectric material to form filament-shaped transmission which can change the refractivity, and moving the sample for making the filament move transversely in the sample to form a refractivity change layer which is just the planar light waveguide. Its advantages are high speed and high accuracy. |