Nonlinear absorption in CdS semiconductor microcrystallines doped phosphorous glass

• Main Authors: Yi-Lien Tu, 杜宜蓮
• Other Authors: Tsai-Chuan Wen
• Format: Others
• Language: zh-TW
• Published: 2005
• Online Access: http://ndltd.ncl.edu.tw/handle/89562584013643879802

碩士 === 高雄醫學大學 === 醫藥暨應用化學系碩士班 === 93 === Cadmium sulfide ( at room temperature) embedded in phosphorous glass is prepared by a melt and heat-treatment method. A large amount of these nanocrystals appear as dark ball shape with radius roughly ranging from 5 to 20 nm by the TEM analysis. A Q-switched Nd:YAG laser delivery linearly polarized pulses at 532 and 1064 nm wavelength with ~6 nanosecond pulse width are employed as light source for the nonlinear absorption experiments. For our 532 nm incident pulses with , the nonlinear attenuation can be attributed to the two photon absorption (TPA) and the free carrier absorption (FCA) above the band gaps of these quantum dots; where the free carriers are suggested to be generated by the process of TPA. The propagation equation is , where is the TPA coefficient and N is the instantaneous free carrier density given by . We fit these two equations to the data of our open-aperture Z-scan measurements to obtain a =-1.67 (cm/GW) and α = 0.01(cm-1) .Upon excitation with 1064 nm ( ) laser pulses in this CdS doped glass at room temperature, similar results are obtained .We also observed the glasses of phosphorous and silicate photoluminescence properties have different .