Characteristics of filamentation in ZK7 glass by negatively chirped femtosecond laser pulses  

作　　者：YANG JianJun YANG Yang WANG Rui HAN Wei 

机构地区：[1]Institute of Modern Optics,Nankai University,Key Laboratory of Opto-electronic Information Science and Technology,Education Ministry of China,Tianjin 300071,China

出　　处：《Science China(Technological Sciences)》2008年第7期849-856,共8页中国科学（技术科学英文版）

基　　金：the National Natural Science Foundation of China (Grant No. 60637020)

摘　　要：The filamentation characteristics of femtosecond laser pulses in ZK7 glass are in- vestigated experimentally as a function of initial negative chirps. It is found that the filament threshold power grows rapidly and the filament length extends over a long distance with increasing initial temporal chirps. The measurement of supercon- tinuum reveals that the plasma generation process within filamentation becomes weaker as the initial negative chirp increases, leading to a self-guiding long light channel dominated by Kerr nonlinearity. The interference of transverse rings in multifilamentation of the chirped laser pulses is observed as well. Analyses and discussions give an interpretation of this chirp-induced ionization-free filamenta- tion. These results indicate that initial chirps will play a crucial role in the filament formation of ultrashort laser pulses in transparent media.The filamentation characteristics of femtosecond laser pulses in ZK7 glass are investigated experimentally as a function of initial negative chirps. It is found that the filament threshold power grows rapidly and the filament length extends over a long distance with increasing initial temporal chirps. The measurement of supercontinuum reveals that the plasma generation process within filamentation becomes weaker as the initial negative chirp increases, leading to a self-guiding long light channel dominated by Kerr nonlinearity. The interference of transverse rings in multifilamentation of the chirped laser pulses is observed as well. Analyses and discussions give an interpretation of this chirp-induced ionization-free filamentation. These results indicate that initial chirps will play a crucial role in the filament formation of ultrashort laser pulses in transparent media.

关 键 词：femtosecond FILAMENTATION CHIRPED laser PULSES SUPERCONTINUUM generation KERR nonlinearity 

分 类 号：TN24[电子电信—物理电子学]