A dispersive modulator

Amplitude modulation and temporal compression of 10-μ light at a frequency up to 80 MHz were demonstrated using a dispersive molulator - a NH3 vapor cell with a near-resonant time-dependent transition frequency controlled externally via the Stark effect. The peak output intensity was observed to be higher than the input intensity, showing that compression effects due to the time-dependent dispersion are essential in determining the output waveform.