Abstract
The major concern of the thesis is to develop the technique to extend the bandwidth of the electric pulse excited by ultrashort lasor pulses. We attempt to achieve this goal by synthesixing bipolar waveform and therefore eliminate the DC component of the electric signal, which will be more efficient to radiate. Non-uniform illuminating excitation was first applied to generate ultrashort electric pulses We obtained pulses with FWHM of barely 190 fs for which bandwidth is broader than 1.1 THz. Secondly, using two pump beams to excite two contiguors photoconductive switches, which were opopositely biased, was employed to synthesis a bipolar ultrafast electric puls. We demonstrated successfully that bipolar pulse synthesis method could significantly improve the bandwidth and eliminate the DC component us well. The synthesis of the bipolar ultrafast electric pulse also suggests the possibility of synthesizing usltrafast waveforms.