Pulse shape control of a mopa fiber laser for marking of stainless steel and other materials

The effects of peak power and pulse width on color marking of stainless steel is demonstrated using a pulsed 1064 nm MOPA fiber laser. A variety of dark mark intensities are achieved by changing the peak power and pulse width of incident beam, without change of incident pulse energy or repetition frequency. This process is demonstrated by maintaining constant pulse energy, scan rate, repetition frequency, average power and spot size. It is consequently shown that surface oxidation and dark mark formation is also dependent on pulse peak power, and is best carried out using pulses that are less than 50 ns wide, with irradiance levels of above 70 MW/cm2. SEM EDS analysis also shows elevated levels of oxygen and carbon. The dynamically controlled MOPA fiber laser is also shown configured for dynamic pulse control for delivery of pulse bursts that can be readily used for temperature sensitive processes such as this one.