Nonlinear optical properties of azo-dye-doped polymer dispersed liquid crystal films using Z-scan technique

• Main Authors: Chin-Hui Chen, 陳錦慧
• Other Authors: Andy Y.-G. Fuh
• Format: Others
• Language: zh-TW
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/31817763483049914524

碩士 === 國立成功大學 === 物理學系碩博士班 === 96 === This thesis explores the nonlinear optical properties of nano-sized liquid crystal droplets azo-dye-doped polymer dispersed liquid crystal（ADDPDLC ) films using Z-scan technique, which is a simple but powerful technique to measure the optical Kerr constant of materials. The measurement of the optical Kerr constant using Z-scan technique is based on the principle of spatial beam distortion due to the self-focusing or self-defocusing that are associated with the intensity-dependent refractive index of the material. Firstly, the nonlinear refractive index of azo-dye-doped LC film is investigated using the Z-scan technique. The results indicate that the optical Kerr constant (n2) of this material is large resulting from the thermal effect and photoisomerization effect. Thus, the optical Kerr coefficient n2 of azo-dye-doped LC film can be modulated by changing the temperature of the sample. In addition, the optical Kerr coefficient n2 of the azo-dye-doped nano-sized PDLC film at various temperatures is also measured using Z-scan technique. The maximum n2 of the azo-dye-doped nano-sized PDLC film is at~ 35 oC.The cause is due to the decrease of clearing temperature of ADDPDLC films. The clearing temperatures for the liquid crystal (E7) used in this work, and ADDPDLC are found to be 61 oC and 43 oC , respectively.