Z-Scan Measurement of the nonlinear optical

• Main Author: 李俊誼
• Other Authors: Wen-Feng Hsieh
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/11640478954112736486

碩士 === 國立交通大學 === 光電工程所 === 90 === By using a femtosecond Ti:sapphire laser (wavelength = 820nm) as z-scan light source, we have studied intensity dependent nonlinear refractive index of the ε-GaSe single crystal grown by Vertical Bridgman growth method . We not only measure the two photon absorption coefficient to be 13.28±0.2 cm/GW, but also the third order nonlinear refraction index coefficient γ= ﹣3.779x10-13cm2/W and the fifth order nonlinear refraction indexσ=1.25x10-18cm3. By rotating the incident angle of the crystal axis with respect to the optical axis of the laser beam, we verify the negative refraction index atθ﹥5° by cascadeχ(2):χ(2) process .Furthermore the effective χ(3) becomes positive for θ< 5°