Temperature dependence of the optical Fréedericksz transition in dyed nematic liquid crystals

Reversible Photoinduced Anisotropy of Azoxybenzenes in Nematic Liquid Crystal Phase and in Solid Polymer Solutions

“…В этом случае нелинейно-оптические явления могут проявляться как через нагрев слоя или фотохимических изменений дипольных моментов оптических переходов и поляризуемостей самих ЖК-молекул или примесных молекул, так и через влияние оптически возбужденных состояний моле-кул на структуру ЖК [7][8][9][10][11].…”

Mechanisms of giant optical nonlinearity in light-absorbing liquid crystals: a brief primer

“…The effects were in all respects similar to those that had been observed in transparent materials, but they were so strong that could be easily induced by means of a He-Ne laser of few milliwatts (therefore they were characteristically colored "red" instead of the usual "green" of the Argon laser light, as shown in the following figure). Some clever experiments performed in the following years by Jánossy and coworkers demonstrated beyond any doubt that the nonlinearity was still orientational and not for example "trivially" thermal (see section 5) [13,14,15]. We recall here some of the main experimental evidence: (i) different dyes with the same absorption coefficient give rise to completely different nonlinear effects, contrary to what would be expected for thermal effects; (ii) the angular dependence of the nonlinearity was that expected for the orientational response; (iii) the relaxation time was of the right order of magnitude for an orientational response; (iv) more exotic dynamical effects occurring when the light is circularly polarized were also found to be identical to those observed in transparent materials, except for a two-orders of magnitude reduced intensity.…”

Dynamical Study of Guest-Host Orientational Interaction in LiquidCrystalline Materials

“…Experimental works subsequent to Jánossy's discovery [8,9,10] showed that while the effect relies on optical excitation of the dye, it is not thermal in nature, as different dyes with the same absorption strength yield different enhancement effect. The enhanced reorientation could have either positive or negative sign, i.e.…”