Nano-quasi-grating of optical diffraction on special stainless steel by a femtosecond-pulsed laser

• Nano-quasi-grating for optical diffraction in special stainless steels is the first report on the raster application.
• The optimum laser fluence (power) matching a right laser scan speed could create a good surface optical grating structure by FS-pulsed laser.
• Whether a clear periodic structure or a new compound formation is the main factor that influences their optical diffraction.

The optical grating on the special stainless steels can be faithfully processed by a femtosecond pulsed laser. At the heat inputs of 0.05 mJ/mm and 0.2 mJ/mm, the optical diffraction illustrated that symmetric double peaks occurred at the diffracted angles of approximately ±13.4° and ±6° for the single phase of 254 SMO. As for the duplex phase of SAF 2205, the optical diffraction only appeared at the diffracted angle of ±13.8° under the heat input of 0.05 mJ/mm, whether a clear periodic structure or a new compound formation is the main factor that influences their optical diffraction.