The ability to reversibly photo-pattern an infinite variety of high-quality, high-resolution alignment domain orientations and shapes makes photoswitchable LC devices ideal candidates for laser applications where electro-optical spatial-light modulators cannot be used due to their low laser-damage resistance (typically, 230 mJ/cm2 at 2.4 ns, 5 Hz at 1053 nm). Such all-optical devices also have the advantage of their inherent simplicity (no electrical interconnects or driver electronics) and convenient in-system write/erase capability. Azobenzene-based photoswitchable alignment materials are excellent candidates for such devices by virtue of their high laser damage thresholds at 1053 nm, which range from 24-66 J/cm2 (1.4 ns pulse). In this work, LC devices fabricated with commercial azobenzene photoalignment layers were exposed to a series of varying optical patterns that were sequentially written, erased and re-written into the assembled devices using either contact photolithography with a xenon/mercury high-pressure arc lamp source or a 433 nm diode laser. These devices were capable of being written, erased and re-written in excess of 30 times without showing significant image burn-in or loss of patterning resolution. Amplitude beam shaping of a 500 mW Nd;YLF 1053 nm laser beam in a laboratory bench-top setup was demonstrated using photoswitchable LC devices in which the beam-shaping profile had been written using the 433 nm diode laser setup and photolithography mask in a bench-top image relaying setup. Similar optical patterning experiments conducted on a series of new photoalignment materials synthesized in-house have shown one example in which written optical patterns have remained stable for more than 4 months under ambient conditions.
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