Emtosecond Laser Fabricating Sub-wavelength Periodical Grating Structures and Its Optical Properties

Sub-wavelength periodical grating structures on tungsten surface was fabricated by femtosecond laser whose central wavelength is 800 nm and the repetition rate is 1 k Hz. The period of the structures was349-620 nm when the laser incidence angle was 0°-80°. The formation of grating structures on tungsten was discussed by surface plasmon polaritons theory and the result of experiment showed a good agreement. The reflectance spectra of these grating structure was simulated by rigorous coupled wave analysis method. The enhanced absorbtion peak was closed to the grating period. This study gives a prospect of applications by femtosecond laser fabricating grating structures.