用光脉冲单周期化的方法产生几个飞秒宽的超短光脉冲

Albeit that much progress has been made during the 90's ever since the modelocking and pulse compression emerged in the 60's, it is still worthy arguing about the limit of pulse compression. When output pulses from Ti:s laser are fed into optical fiber, they can be compressed down to 5fs by exploiting the SPM effect to broaden the spectra. This pulsewidth is only two optical cycles. Does this imply an ultimate limit of ultrashort laser pulse? The present proposal is aimed to break through this limit by using single-cycle method, hoping to produce pulses of 1-2fs or even shorter duration..This project has fulfilled the following work: (1)Theoretically, the SPM and XPM mechanisms and their mutual interaction within fibers are used to produce single-cycle pulses. Fourier transform theory was used to analyse the propagation of multi-pulse in fiber. The effects of varying initial pulse conditions and fiber parameters on the spectral broadening are simulated. Numerical results indicated a super wide spectrum of up to 800THz, with an ideal temporal width of 1.014fs and pulse envelope. (2) Through computer simulation and experiments, the FROG technique has been setup. It can detect the amplitude and phase of ultrashort optical pulses, and no similar report was seen at home. (3) Base on the theoretical research, we setup a modelocked oscillator and amplifier system through collaboration with the Institute for High Energy Physics. Spectral broadening and pulse compression experiments were performed. The results were, however, not what we had anticipated. We but gained experiences which will benefit our future studies..

利用谐波频率等间隔而且相位同步的三个飞秒光脉冲输入到光纤中，使其产生互感应相位调制效应（MIPM），这种MIPM效应对光谱的展宽比只有自相位调制（SPM）时高深莫测倍，使馄椎玫匠浞值恼箍恚俳渫ü占湎辔坏髦破鹘杏行У难顾趵椿竦玫ブ芷诨?---3fs光脉冲。这种利用MIPM+SPM效应相结合产生单周期化光脉冲的方法是获得<10fs超短光脉冲的峦揪丁