1 064 nm Laser Damage on Indium Tin Oxide Films

Liquid crystal optical elements have important applications in laser facility, and the indium tin oxide (ITO) films are generally used in liquid crystal optical elements as transparent conductive electrodes. Laser induced damage of ITO films leads to failure of liquid crystal optical elements. The laser damage model of ITO films which simulates the temperature distribution and thermal stress distribution was established. The laser damage of ITO films was experimented through pump-probe technology, and the power density producing damage at a probability of 50% (i.e., damage threshold) was obtained by 1-on-1 testing, and the square resistance of the film after laser irradiation was also measured. The experimental data basically agree with the simulated results. The results show that 1 064 nm laser damage of ITO film occurs mainly by thermal stress. The damage of ITO film begins from K9 glass substrate after CW laser irradiation, while the damage begins from the surface of ITO film after pulsed laser irradiation. Furthermore, the laser damage thresholds decrease with the increase of thickness of ITO films. The square resistance of ITO films increases with the increase of laser intensity unless the ITO films have been damaged completely. The optimal thickness of ITO film in liquid crystal optical element depends on the factors of laser damage, transparence and square resistance.