Due to the thermal deposition, the switching ratio of the amplitude OASLM will be reduced, so it is difficult to play a better effect in the high average power laser system. In this paper, through the analysis of laser-induced temperature rise model and liquid crystal layer voltage model and experiments, we show that with the same aperture and same switching ratio, the tolerable optical power density will decrease with the larger irradiation spot area. When the spot diameter decreases from 8 mm to 3 mm without heat dissipation treatment, the temperature of the OASLM emitting surface decreases from 39.6 °C to 33 °C, and the laser tolerated power density improves from 32.8 W/ cm2 to 120 W/ cm2, but the total tolerated power decreases from 16.5 W to 8.5 W. Therefore, in order to improve the total power tolerance of the optical addressable spatial light modulator, it is still an important technical way to improve the clear aperture of the optical addressable spatial light modulator.
In this paper, in order to provide theoretical support for the higher laser damage resistant Optically-Addressable liquid crystal Light Valve (OALV) technology research, the laser damage model of liquid crystal optical devices under high power laser is established, and the damage characteristics of optically addressed spatial light modulators based on Si-doped gallium nitride (GaN) electrode and based on indium tin oxide (ITO) electrode are researched. Their thermal distribution and thermal stress under high power laser are analyzed respectively. The results show that the laser damage threshold of liquid crystal device with ITO electrode is only 500 mJ/cm2, and the GaN electrode is several times larger than the former under pulse laser irradiation, the electrode of both liquid crystal devices are damaged first. Under the irradiation of high average power laser, the liquid crystal device of ITO electrode will reach the clear point first because of the thermal deposition. However, in liquid crystal devices with GaN electrode, the temperature rise of liquid crystal is small and the temperature distribution is uniform. GaN electrode has better thermal stability than ITO electrode under cooling measures. This undoubtedly shows that liquid crystal optical devices with GaN electrode have a good development potential in high power laser systems.
This paper introduces the recent development of our integrated optical addressed spatial light modulator and its applications in the high power laser systems. It can be used to convert the incident beam into uniform beam for high energy effiency, or it can realize special distribution to meet the requirements of physical experiment. The optical addressing method can avoid the problem of the black matrix effect of the electric addressing device. Its transmittance for 1053nm light is about 85% and the aperture of our device has reached 22mm× 22mm. As a transmissive device, it can be inserted into the system without affecting the original optical path. The applications of the device in the three laser systems are introduced in detail in this paper.
In the SGII-Up laser facility, this device demonstrates its ability to shape the output laser beam of the fundamental frequency when the output energy reaches about 2000J. Meanwhile, there’s no change in the time waveform and far field distribution. This means that it can effectively improve the capacity of the maximum output energy.
In the 1J1Hz Nd-glass laser system, this device has been used to improve the uniformity of the output beam. As a result, the PV value reduces from 1.4 to 1.2, which means the beam quality has been improved effectively.
In the 9th beam of SGII laser facility, the device has been used to meet the requirements of sampling the probe light. As the transmittance distribution of the laser beam can be adjusted, the sampling spot can be realized in real time. As a result, it’s easy to make the sampled spot meet the requirements of physics experiment.
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