ELECTRON-DENSITY WAVES AND ULTRASHORT IR PULSE GENERATION.

It appears promising to use a gas (under gas-discharge conditions), where the free-electron concentration can be altered considerably by collisional ionization or photoionization, or alternatively a semiconductor, where band-band or impurity absorption may alter free-carrier concentration substantially, while absorption within bands may alter critical carrier density. The name electron-density wave (EDW) is given to the region of elevated free-carrier concentration produced by the pulse and propagating with it; the reaction from the EDW on the pulse produces AM and FM, and it is evident that this modulation will increase with LAMBDA . Here we show that one can use this effect to obtain ultrashort pulses in the IR range.