New Detector Measures Waveforms of Pulsed Laser Light
23 January 2014
Researchers at the Laboratory for Attosecond Physics at the Max Planck Institute of Quantum Optics in Germany have developed a simplified detector that can measure the waveforms of pulsed laser radiation, bringing work towards gaining complete control over the waveform of pulsed laser light to a new level.
The achievement is a significant success since the device can give a detailed picture of the waveforms of laser pulses, which exist for just a few femtoseconds.
The detector is made of glass and measures the flow of electric current between two electrodes that is released when the electromagnetic field corresponding to the laser pulse hits the glass. By examining its properties, the induced current can then tell the exact waveform of the pulse, which enables the generation of light flashes lasting only for attoseconds. This can be used as a basis for examining ultrafast processes at the molecular and atomic levels.
The glass-based detector was combined with a conventional instrument to measure the waveforms of light, enabling the identification of the currents caused by the movements of the electrons liberated from atoms of xenon, the gas used for the experiments. These measurements, in general, must be performed in a high vacuum environment and when comparing the currents induced in the new detectors with the data derived from the conventional devices, the performance of the glass-based apparatus can be characterized, which makes it a reliable phase detector for few-cycle femtosecond laser pulses.
Deriving a precise waveform of the laser pulse allowed the researchers to reproducibly generate stable trains of ultra-short attosecond light flashes. Each of the flashes is a thousand times shorter than the pulse that induced it. These attosecond flashes can be used for recording the movement of electrons in atoms or molecules by just tuning the length of the flashes to the material of interest.