Study On The Damage Of Optical Films By Short Pulse And Femtosecond Pulse Laser

Along with the development of laser technology, the durations of laser pulse have been compressed successfully from ns to the order of fs, and with the improvement of laser pulse peak power, as a result, the research on the interaction between laser and materials has been advanced to completely new stage. As the essential basic component of almost all optical systems, optical films are the weakest link in the whole systems, thus ,the laser damage of optical thin films has been the bottleneck of high-energy, high-power direction of lasers. Therefore, it is very significant and valuable to research the damage of optical thin-film by lasers.The damage of optical thin films by pulsed laser is a complex process, it is often accompanied by the emergence of several mechanisms of damage. The damage of optical thin films by the short pulse laser and the femtosecond pulse laser is analyzed in this paper. First, from short pulse laser damage, and then, it is extended to the femtosecond pulse. Through the establishment of thermal shock effect model, we solve the temperature distribution and thermal stress distribution of diamond-like carbon and aluminum reflector in short pulse lasers. On this basis, we compress the laser pulse from the order of nanosecond to femtosecond , introduce several classical energy transport models in the femtosecond laser pulse. By constructing a two-temperature and two-step model, discussing the damage of optical thin films in 200nm gold film by the femtosecond pulse laser. It suggests that the laser damage threshold of materials disobeys the ? 1/2 law, it can not be treated by the classical fourier thermal conduction theory.