Self-focusing and limiting at nanowatt laser power and image conversion with μWatt/cm2 optical intensity using nematic liquid crystal films

Reports on the observation of an extraordinarily large purely optically induced refractive index change mechanism in methyl-red dye doped nematic liquid crystal film. A refractive index change coefficient of 6 cm²/W. is obtained. Visually observable self diffraction and holographic grating diffraction, incoherent→coherent image conversion and optical limiting effects can be generated with optical intensity as low as 40 μW/cm². The response times are measured to be in the milliseconds regime. The liquid crystal used is 5CB with pentyl cyano methyl-red dissolved in it at a concentration of about 1%