Abstract
Abstract In this paper, we propose an effective method to compensate for the performance degradation of optically addressed spatial light modulators (OASLMs). The thermal deposition problem usually leads to the on-off ratio reduction of amplitude OASLM, so it is difficult to achieve better results in high-power laser systems. Through the analysis of the laser-induced temperature rise model and the liquid crystal layer voltage model, it is found that reducing the driving voltage of the liquid crystal light valve and increasing the driving current of the optical writing module can compensate for the decrease of on–off ratio caused by temperature rise. This is the result of effectively utilizing the photoconductive effect of Bi12SiO20 (BSO) crystal. The experimental results verify the feasibility of the proposed method and increase the laser withstand power of amplitude-only OASLM by about a factor of 2.5.
Highlights
In the past decade, liquid crystal spatial light modulator (LCSLM) is widely used in panel display, beam control, adaptive optics, laser processing and other fields because it can precisely control the beam amplitude, wavefront, polarization and other parameters by changing the effective birefringence of liquid crystal [1,2,3,4,5]
The results show that the transmittance of optically addressed spatial light modulators (OASLM) increases continuously with the increase of temperature until the liquid crystal light valve loses its effect
The laser model results show that the heat source of OASLM is mainly concentrated in the indium tin oxide (ITO) layer on the BSO side, and the temperature of the liquid crystal layer is mainly affected by the temperature of the ITO layer inside the liquid crystal cell
Summary
Liquid crystal spatial light modulator (LCSLM) is widely used in panel display, beam control, adaptive optics, laser processing and other fields because it can precisely control the beam amplitude, wavefront, polarization and other parameters by changing the effective birefringence of liquid crystal [1,2,3,4,5]. Cao et al reported that the increase of temperature led to the phase transition of liquid crystal and changed the light intensity in the laser irradiation area [18]. There are few reports on the damage mechanism and optical properties of amplitude type OASLM irradiated by high repetition frequency or continuous laser. We build a laser-induced model based on the OASLM of BSO crystal to evaluate the thermal effect of OASLM under high power CW laser On this basis, the effect of temperature on the transmittance of OASLM is studied. Only by adjusting the driving voltage of the liquid crystal light valve and output intensity of the optical writing module, the OASLM can operate normally for a long time under high power CW laser irradiation without any external heat dissipation measures
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