Detector Details Waveforms of Laser Pulses

A simplified detector for measuring pulsed laser radiation takes an important step toward complete control over the waveform of pulsed laser light, a necessary development for highly sensitive and reliable measurements of ultrafast physical processes.

The new glass-based phase detector, created by a team from the Laboratory for Attosecond Physics at the Max Planck Institute of Quantum Optics, the Ludwig Maximilian University of Munich and the Technical University of Munich, provides a detailed picture of the waveforms of few-cycle femtosecond laser pulses.

A mode-locked laser emits flashes of light that last for a few femtoseconds. A new glass-based phase detector enables more precise control of pulse waveforms for studying processes at the molecular and atomic levels. Courtesy of Thorsten Naeser.

In the past few years, the team found that when pulsed high-intensity laser light impinges on glass, it induces measurable amounts of electric current in the material. The team recently discovered that the direction of flow of the current generated by an incident femtosecond pulse is sensitively dependent on the exact form of its wave packet.

The new detector measures the flow of electric current between two electrodes to determine the precise waveform of the pulse from the properties of the induced current. Knowing the pulse’s exact waveform makes it possible to generate light flashes that are a thousand times shorter – lasting only attoseconds – and can be used to study ultrafast processes at the molecular and atomic levels.

In its practical application, the technique allows the waveforms to be more easily controlled than with traditional methods, such as gas-phase detectors.

The work was published this month in Nature Photonics.

For more information, visit www.mpq.mpg.de.