Dynamic response of a cw laser-produced Cs plasma to laser modulations

We present a first experimental investigation of the response of a continuous laser-produced Cs plasma to weak modulation of the laser beam. The cw dye laser beam at 6010.49 Å, of ∼0.1 W power, excites the Cs (6P1/2→8D3/2) atomic transition in the present study. At low modulation frequency, the fractional modulation of the transmitted laser beam is greatly reduced from that of the incident beam. At high modulation frequency, the two fractional modulations are nearly equal. We also demonstrate that the normal amplitude fluctuation of the laser beam is greatly reduced after transmission through the plasma. These features of the dynamic response are explained in a simple rate equation analysis.